Cylinders for lock casings are available in two standard types, Euro Profile and Oval Profile. These recognised standards now cover practically all types of lock cylinder with the difference being the shape of the cylinder. Both Oval and Euro Profile cylinders are available in varying lengths to suit different door thickness. Each shape can also be purchased as a half cylinder which can only be locked from one side of the door or a thumbturn cylinder which includes a key on one side and a thumbturn on the other.