MK17 AA Spider Sight, .50 cal., ANM2 or M3, with bracket. ‘Original’ US GI WWII, Extremely RARE Anti-Aircraft sight for the MK21 Naval Gun Mount. Bracket attaches over the trunnon mount of a Browning ANM2 or M3 fifty caliber machine gun. The Spider Sight is NOS. The Sight Bracket is Restored. US GI, NOS Condition.