The Mask HD is the first rimfire can from Dead Air Armament. It is full auto rated for a variety of 17 and 22 caliber rimfire as well as 5.7x28FN.
Most shooters comment on its pleasant, deep tone. However, I was most impressed with its performance on my FVSR. Nearly as quiet as a dryfire, the Mask HD had negligible POI shift or impact on the size of my groups.