I just got mine in today and I am quite satisfied with the quality of the piece. As the manufacturer says it simply tucks in between the forearm and it's retaining band. Although it is made in Canada and it's about $50, I think it is a much more durable solution to the "big buttons" offered by other companies. Not only does it not interfere with anything else, it cannot damage the bolt release mechanism and I can easily get three fingers on it as shown.
From one who was trained by one of Uncle Sam's Misguided Children, I am very impressed with the ingenuity and military simplicity of this piece: nothing to break or go wrong here.