A thread popped up in the Silencer forum about the HAL-GM and it's compatibility with various devices.
There are 3 different generation HALOs which have different restrictions on which "A2" device works. There's also the Griffin M4SD series which also uses different mounts. Then there's the obsolete AAC OMNI which some still use.
Battle Comp, BCM, Daniel Defense, Griffin, PWS, Vltor, and 2A Armament all make "A2" compatible devices. Some, like BCM, make several styles with different compatibility depending on which can or generation you're looking at. Gem-Tech is also making their new bi-locks A2 compatible.
So it seems like there's a host of "A2" mounts that may or may not work with a users A2-compatible can. Would Silencer Shop be willing to put together a compatibility chart for these A2 cans and devices? I really like my M4SDK and I think it would sell A2 cans if consumers knew how versatile they are.