heavy duty staple gun tacker all steel construction steel working parts chrome finish jam proof mechanism refill window double leverage operation use heavy duty t50 staples 1/4" (tv# 137-190), 5/16" (tv# 137-364), 3/8" (tv# 137-406), 1/2" (tv# 139-337), 9/16" (tv# 353-562) & 17/32"/ct (tv#140-053) staples-narrow crown.