Hu-Du 300 Win Mag Muzzle Brake. 5/8x24, works with calibers less than .308. No longer need as I am running suppressor. Works ridiculously good. There are videos on youtube with guys shooting 300wm off their chin. Will need new crushwasher. There are few little wear marks here and there, otherwise good condition.

See link for specs:

https://www.sptdefense.com/product/Hu-Du-300-Win-Mag-Black-5-8-24