Meant for the IS-2/ISU-122, there are pretty much only two kits on the market for this set, those being from PST. ARMO also produces a muzzle-less version of this gun for the ISU-122, and this Aber piece is the only one available with muzzle brake.

This is a superb set, and I highly recommend it.

Thank you very much to Chris Kowall for the providing the review item.