This is a clever and attractive design. The spring-loaded button body traps a tapered pin to lock a lid.
Installation is easy; only three holes need to be drilled. Instructions included. The pin has a tapered groove near the base to help provide a mechanical lock when glued, and requires a hole 15mm deep to be drilled in the lid.
Button case diameter is 15mm, and is centered 10mm down from the box lip. The exposed lock projects just 5mm.