for sale is an ARMS #41-B folding front sight gas block without bayonet lug. Factory new.
This is a popular item in and of itself, and made by a well-known military provider.
A.R.M.S.® #41™-B SILHOUETTE™ Front Folding Sight solves the problem of trying to fold the well known triangle shape of the conventional non folding front sights. Barrel mounted in place. Utilizes a rugged spring loaded angled support system to eliminate getting caught up in brush and other combat hazards. Made of steel and also uses the standard front sight post.