The A.R.M.S 40L-F is a Low profile rail mounted fold down front sight. The unique design of the spring loaded front sight ensures constant in battery action and repeat zero. The sight is held in the locked down position by a quick release lever, that prevents the sight from being accidentally engaged, but is as fast as a trigger to release even with arctic mittens. Additionally the 40L-F™ utilizes the same front sight post as a standard M-4/ AR-15 and can be fitted with most aftermarket sight posts.