Back on topic..is the KAC A1 length or A2 length? That Sierra one looks like it would add too much length for me even on an A1, and to be honest I'd rather a riser than LOP adjustment. This looks cool http://www.bradleycheekrest.com/The-Bradley-A2-Adjustable-cheek-rest-For-the-A2-AR-stock-NEW-BA-000-TAC-BLK-A2.htm