Designed for hard-use applications, the Superlative Arms gas piston system uses patented Bleed Off Mode to vent gas outward, maintaining consistent performance without the drawbacks of flow-restricting blocks. Gas adjustment (patented) - features 30 fixed positions located at the front of the block Bleed-off port (patented) - located at the front of the block, designed to vent forward, directing emissions away from the operator 3/4 inches x 1 inches clamp-on QPQ melonite 416 stainless steel piston gas block Left-handed, fully automatic AR-15 bolt carrier, dark DLC coated, 8620 steel Carbine gas system/operating rod length