Yankee Hill Machine Co Nielsen Pistons, 45 Cal, .578-28, Stainless Steel, Compatible with YHMs Booster Housing YHM-2055 as Well as Many Popular Pistol Suppressors, Silver YHM-2062-28 YHM's Nielsen Pistons are compatible with YHM's booster housing YHM-2055 as well as many popular pistol suppressors. They are constructed from heat treated 17-4 stainless steel for maximum durability and corrosion resistance. They feature 10 adjustment points to zero any impact shift. Available in a variety of thread patterns to fit most firearms.