Brand: Beta Tools
The 710 Series 3/8" drive impact sockets and accessories from Beta Tools feature cross-drilled holes at the drive ends to accept a locking pin. The locking pin doesn't transmit any torque (that's the job of the square drive), but it keeps sockets and extensions from rattling apart.
This short pin is designed specifically for 710 Series sockets with 7mm through 12mm hexes (19mm base OD). Sold individually. The matching Beta Tools 710/OR1 Retaining O-Ring is sold separately.