no worries Report post Posted July 7, 2021 Blake nitrate 4 port design. Locking collar to adjust timing. 3/4 x24 threads. 30 cal. I bought this a couple years ago from a rifle builder. It looks new but I believe he fired some rounds thru it. He said the brake was made by PVA , not sure which model. $75 located in sunny Tucson Share this post Link to post Share on other sites