Square-head plug

A square-head plug is a forged threaded closure for a threaded opening, identified by its external square tool-engagement head. That head geometry distinguishes it from a hex-head plug but does not by itself prove higher torque capacity, strength, or easier removal. The title also does not establish thread form, internal body construction, material, or class. Selection should verify the male thread and mating opening, sealing method, tool clearance for the square head, material, service conditions, and the intended removal or maintenance plan.