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. Brass plated.