Union C-series 3K70 - 5 Detainer Sashlock (73mm, Polished Brass) R/H

£157.18
Customer Reviews
Rated 4.8

/5

Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5
5 Reviews

100%

Recommended
this Product
Ease of Use
Out of 5
4.9
Build Quality
Out of 5
4.9
Summary of 5 customer reviews
Customers say this Union lock is a perfect replacement for older models, often fitting directly into existing door cutouts. Many highlight its excellent build quality, comparing it favorably to durable, decades-old locks it replaces. Users found the installation straightforward, making it an easy DIY job. The price is considered competitive, offering good value given the avoidance of door modifications.
Easy Install
Perfect Match
Good Quality
Competitive Price
Good Value

See all reviews

The Union C-series 3K70 (Previously by Chubb locks) includes a deadlock that is locked by Key on either side.
View Full Specification
  • Latch opened by handle on either side.
  • The latchbolt is not reversible and must be fitted to a right hand hung door.
  • Also available for use with a left hand door.
  • Previously by Chubb Locks.
  • 44mm backset from forend.
  • 73mm deep case.
  • 14mm bolt projection.
  • Also available keyed alike.
MPN: 3K70R-73-PB

See all reviews

Details
A 73mm
B 44mm
C 56mm
D 148mm
E 200mm
F 25mm
Dimensions
Case Depth 73mm
Backset 44mm
Centres 56mm
Case Height 148mm
Forend Length 200mm
Forend Width 25mm
Show Imperial »
Lock
Manufacturer Part Number
3K70R-73-PB
Mortice Type
Sashlock
Lock Mechanism
5 Detainer
Key Differs
25,000
Bolt Projection
14mm
Latchbolt
Fixed
Follower
8mm
Backset (keyhole)
44mm
Colour
Polished Brass
Features
Insurance Approved*
No
Handed
Right
Rebated
No
Keyed Alike
Available
In The Box
Lock Case
Yes
Strike Plate
Yes
Keys
2
Reviews [5]
Rated 4.8

/5

Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5
5 Reviews

100%

Recommended
this Product
Summary of 5 customer reviews
Customers say this Union lock is a perfect replacement for older models, often fitting directly into existing door cutouts. Many highlight its excellent build quality, comparing it favorably to durable, decades-old locks it replaces. Users found the installation straightforward, making it an easy DIY job. The price is considered competitive, offering good value given the avoidance of door modifications.
Easy Install
Perfect Match
Good Quality
Competitive Price
Good Value
Ease of Use
Out of 5
4.9
Build Quality
Out of 5
4.9
Sort by:
Philip Verified Customer February 2017
Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5
Recommended

The lock arrived very promptly and at almost the excat time predicted - handy as I was on a tight deadline to fit it myself. The build quality was excellent, the equal of the much older lock it was replacing. I had been concerned that there might need to be alterations made to fit the new lock, imperial to metric having occurred in the intervening fifty odd years, but the new lock was a perfect replacement for the failed original, slotting straight into the door and working smoothly from the outset, indeed the elderly relative for whom I was doing the job could not at first tell the difference at all.

Was this helpful? 11

Anonymous Verified Customer March 2016
Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5
Recommended

This product was bought to replace an existing Chubb lock which was probably original and therefore a lot older than myself. The door is solid oak, and would have been a shame to cut about to fit a more modern (smaller) lock. The web-page gave an excellent description of the product with accurate measurements of all the dimensions, it also made quite clear that this lock had previously been sold as a Chubb. It was the simplest of jobs to remove the old lock and install the new one. Delivery was as promised. If in another eighty odd years when this lock shows sign of wear and needs replacement, I shall know where to come.

Was this helpful? 11

Anonymous Verified Customer October 2018
Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5
Recommended

Excellent web site with good Google profile, making it easier to select product and compare prices. Price was the cheapest that I could find (especially when postage was taken into account), but still feels expensive.....sorry, I still remember when locks were cheap! Service was excellent and product delivered on time. Straight swap for the old lock (probably about 60 years old, but had a broken spring). Only slight problem was that I couldn't re-use the securing screws as they were fractionally too large a diameter for the front plate. Trip to B&Q sorted this. Very happy with purchase and would certainly use Safe.co.uk again.

Was this helpful? 3

Anonymous Verified Customer January 2024
Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5
Recommended

I needed to replace an old mortice lock which had become sticky to open. An internet search turned up this one which was an exact match and fitting it was an easy DIY job, just remove the old one and put this in for an exact match for the positions of the keyhole, handle etc. Good service from seller and a reasonable price and no fear of being locked out

Was this helpful? 1

David Mayle Verified Customer August 2025
Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5
Recommended

Since I was looking to replace a 40 year old lock which was beginning to feel a tad ‘difficult’, like with like was the obvious way to go (really didn’t want to have to start modifying the door, so a cheaper ‘alternative’ would likely be a false economy!).

Well laid out website gave me all the information necessary to ensure a straightforward install, price was fully competitive, and ordering/delivery more straightforward than most.

Was this helpful?  

David Mayle Verified Customer August 2025
Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5
Recommended

Since I was looking to replace a 40 year old lock which was beginning to feel a tad ‘difficult’, like with like was the obvious way to go (really didn’t want to have to start modifying the door, so a cheaper ‘alternative’ would likely be a false economy!).

Well laid out website gave me all the information necessary to ensure a straightforward install, price was fully competitive, and ordering/delivery more straightforward than most.

Was this helpful?  

Anonymous Verified Customer January 2024
Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5Rated 5 / 5
Recommended

I needed to replace an old mortice lock which had become sticky to open. An internet search turned up this one which was an exact match and fitting it was an easy DIY job, just remove the old one and put this in for an exact match for the positions of the keyhole, handle etc. Good service from seller and a reasonable price and no fear of being locked out

Was this helpful? 1

Anonymous Verified Customer October 2018
Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5Rated 4.6 / 5
Recommended

Excellent web site with good Google profile, making it easier to select product and compare prices. Price was the cheapest that I could find (especially when postage was taken into account), but still feels expensive.....sorry, I still remember when locks were cheap! Service was excellent and product delivered on time. Straight swap for the old lock (probably about 60 years old, but had a broken spring). Only slight problem was that I couldn't re-use the securing screws as they were fractionally too large a diameter for the front plate. Trip to B&Q sorted this. Very happy with purchase and would certainly use Safe.co.uk again.

Was this helpful? 3

Philip Verified Customer February 2017
Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5Rated 4.8 / 5
Recommended

The lock arrived very promptly and at almost the excat time predicted - handy as I was on a tight deadline to fit it myself. The build quality was excellent, the equal of the much older lock it was replacing. I had been concerned that there might need to be alterations made to fit the new lock, imperial to metric having occurred in the intervening fifty odd years, but the new lock was a perfect replacement for the failed original, slotting straight into the door and working smoothly from the outset, indeed the elderly relative for whom I was doing the job could not at first tell the difference at all.

Was this helpful? 11

Anonymous Verified Customer March 2016
Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5Rated 4.3 / 5
Recommended

This product was bought to replace an existing Chubb lock which was probably original and therefore a lot older than myself. The door is solid oak, and would have been a shame to cut about to fit a more modern (smaller) lock. The web-page gave an excellent description of the product with accurate measurements of all the dimensions, it also made quite clear that this lock had previously been sold as a Chubb. It was the simplest of jobs to remove the old lock and install the new one. Delivery was as promised. If in another eighty odd years when this lock shows sign of wear and needs replacement, I shall know where to come.

Was this helpful? 11

Accessories

Add at Checkout

Thumbnail of Asec Spare Key

Spare Key

Keys are of course included, but we can cut you a spare.
Please allow 4 additional days for delivery.
£7.20
Delivery

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Next / Named Day Delivery to your front door on a day of your choice
Order Now Get It Tue 17th Feb
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Scottish Highlands Delivery Includes doorstep drop off deliveries to the following Highlands post codes, no steps: AB30-38, AB44-56, FK17-99, G83, IV1-39, IV52-54, IV63, KW1-14, PA21-33, PA34-40, PH18-26, PH30-41, PH49-50
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Scottish Islands Delivery Includes doorstep drop off deliveries to the following Scottish Island post codes, no steps: HS1-9, IV40-51, IV55-56, KA27-28, KW15-17, PA20, PA41-49, PA60-78, PH42-44, ZE1-3
Mon-Fri
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Northern Ireland Delivery Our standard doorstep drop off service, no steps
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Guernsey Delivery Our standard doorstep drop off service, no steps
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Returns

Returns

Replacements
If you are not completely satisfied with your purchase, simply complete our returns form within 14 days of receiving your order. Goods must be returned within 30 days of the delivery date, in their original condition and packaging.
More information about returns
FAQs [1]

FAQs (1)

» Ask Question   

 
Hello - when it says, use with a left hand hung door. Is that looking from the outside of the house or inside looking out?
Edward Evans, Southsea
When trying to determine if you need a left or a right handed door lock, stand on the outside of the door. If the lock is on the left, you need a left handed lock. If the lock is on the right, you need a right handed lock.
Jonathan P
Was this helpful? 16
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Keyed Alike

Keying Options

Keyed to Differ or Keyed Alike locks?

As standard the Union C-series 3K70 - 5 Detainer Sashlock (73mm, Polished Brass) R/H is supplied Keyed to Differ which means the lock includes a set of keys that are unique and will only open this lock. If you require multiple locks you can choose to have them all Keyed Alike, meaning that each lock can be opened using the same key.

What is Keyed to Differ?

  • Keyed to Differ is the standard way a lock is supplied.
  • Each lock is opened by its own unique key.
  • Each lock includes a unique set of keys.
  • Covered by our returns policy.

What is Keyed Alike?

  • Each key can open multiple locks - the same key could unlock your house and office.
  • Locks need to be the same brand and number of levers.
  • Keyed Alike locks include one set of keys regardless of how many locks are purchased.
  • Made to order so NOT covered by our returns policy.
  • It is possible to order this lock Keyed Alike here