Precision Reflex .875 Adjustable Gas Block w/Straight 15.165 inch Gas Tube Black. Gas block #10-32 adjustment set screw. Gas block held in place by 2 10-32 set screws. Gas block is 1.61in tall 1in in length and is .780in from bore center to gas tube. Block is 1.155 in width and comes with roll pin. Gas block will not fit under most hand guards because of the extra elevation to get adjustment screw between gas tube and barrel. The height from barrel center line and the gas tube is .78in. This set up works on AR15 rifle length gas systems and DPMS 308 gas system lengths. The dimension from bore center to the top of the gas block is .940in. From the back of the gas block to the gas port hole is .250. This leaves .035 between the back of the gas block and most steps in the barrel. This is for installing of the A2 style hand guards. So there should be a .035 gap between the barrel step and the gas block. This can be filled with spacer or leave empty. The overall Length of the straight gas tube is 15.165in Specifications for Precision Reflex Adjustable Gas Block w/Straight 15.165 in Gas Tube: Manufacturer: Precision Reflex Color: Black Fabric/Material: 1141 High Strength Steel Gun Make: AR Platform Condition: New Package Contents: Precision Reflex Adjustable Gas Block w/Straight 15.165 in Gas Tube Precision Reflex 05-875-02GT: .875 Adjustable Gas Block w/Straight 15.165 inch Gas Tube Black