This depends on where you’re using it and which type of handle you have. For a sprung lever handle, a standard sash lock will suffice, but for our unsprung lever handles, you’ll need a heavy-duty sash lock to help return the lever to its horizontal position. On bathroom doors with a sprung lever handle, a standard lock should be suitable, and for bathroom doors with an unsprung lever handle, a heavy-duty bathroom look will be required. Either a standard or heavy-duty bathroom lock should be suitable for a knob set and thumbturn on a bathroom door. For external doors with a centre door knob or cylinder pull, a stand-alone deadlock can be used.

This depends on which door furniture you’re planning to use. With a lever handle, a 2.5” or 3” lock should be suitable. However, if you’re using a door knob, we recommend using a lock that’s 3” or bigger to ensure the knob is positioned far enough away from the edge of the door frame. If you use too small a lock, you risk catching your knuckles on the edge of the door when trying to turn the knob.

The only difference is the strength of the spring contained within the mechanism. Standard locks have a standard spring which is suitable for sprung lever handles/knobs. Heavy-duty locks have a much stronger spring which gives them the strength required to return an unsprung lever handle or door knob to its original position.