This 3-11/16" long lever is modeled after originals used on early Colonial era longrifles, with sliding wooden patchboxes. This simple, clever, reliable latch mechanism is the choice of today's best longrifle builders, used on fine longrifles. The large knob, at rear, is notched to engaged the buttplate. It must be lifted to unlatch the sliding lid. The end is drilled for mounting with a screw.
This example shows the patchbox spring fitted to a slot, under the patchbox lid. This well made patchbox release latch spring that will serve you well.