Our knobs come unsprung. These are hollow and have loose roses to enable them to be used with a rim lock ( discard one rose) or use with a mortice lock. They have 8mm threaded spindle to take adjustment for various door thickness and lock firmly with a grub screw. For best results the centre of the knob should be a minimum of 3'' from the edge of the door. Heavy Duty latches 4'' or 5'' are recommended for maximum efficiency. Supplied with necessary fixing screws. The GRUB SCREW should locate on the ''V'' in the shaft and not on the threaded part.