The Volquartsen Thread Protector fits 1/2X28 TPI threaded barrels.
It is available in four versions with different materials, dimensions, and product numbers.
Thread Protector, Matte Black Stainless Material: Matte Black Stainless Steel Dimensions: 23.57 mm OD x 11.43 mm (0.928" OD x 0.450") Approximate weight: 42.52 g (1.5 oz) Product Number: VC1228T-B
Thread Protector, Matte Black Aluminum Material: Matte Black Aluminum Dimensions: 23.57 mm OD x 11.43 mm (0.928" OD x 0.450") Approximate weight: 42.52 g (1.5 oz) Product Number: VC1228T-BA
Thread Protector for Volquartsen Barrels for M&P 15-22 Material: Matte Black Stainless Steel Dimensions: 19.43 mm OD x 11.43 mm (0.765" OD x 0.450") Approximate weight: 42.52 g (1.5 oz) Product Number: VC1228T-MP
Thread Protector, Stainless Material: Stainless Steel Dimensions: 23.57 mm OD x 11.43 mm (0.928" OD x 0.450") Approximate weight: 42.52 g (1.5 oz) Product Number: VC1228T-S