Looked at several aftermarket ones before buying. For me, a part like this is best from the manufacturer, and I feel that this was a really good decision. The fit is incredibly tight, zero movement once installed. It actually took a little coaxing with a mallet.

reduced length by almost 1/2 from other back plate. extremely light weight

This is by far the best picatinny rail end cap for the APC. I've tried multiple aftermarket options and none of them come close to the fit, finish, and utility of the genuine B&T part. It's a little expensive, but well worth it when compared to the competition. Wish I would have bought this one first.