Brass Hex Plug Square 15mm from Reece

LTWFITTING 1/2 in. MIP Brass Pipe Square Head Plug Fitting (10-Pack) HF101810 - The Home Depot

Champion Brass Pack Hex Taper Plug HC52, 3/8

Pipe & Fittings

Kinetic 15mm Brass Threaded Hex Plug - 4700224

Flared Fittings

Pipe Thread Faucet Extension Brass Threaded Pipe Connectors - Temu Canada

APPROVED VENDOR HEX SOCKET PLUG,SZ 1/2 IN,L 9/16 IN - Metal Pipe Fitting Caps and Plugs - GGM4WPK5

MIXER CARTRIDGES - TAP ACCESSORIES - TAP SPARES AND ACCESSORIES - PLUMBING

15mm Brass Plug BSP 1/2