Troy .875 Gas Block SGAS875OOBT00. 875 Rifle Gas Block. These easy-to-install AR Gas Blocks from Troy Industries are low profile to allow room for other accessories. Troy .875 Hardened Steel Gas Blocks are precisely machined for excellent fit flawless function and a tactical look. Pick up a Troy .875 Low Profile Gas Block for your next build. Specifications for Troy .875 Gas Block SGAS875OOBT00: Manufacturer: Troy Fabric/Material: 4140 Steel Gas Block Journal Size-Diameter: .875 in Additional Features: Low Profile Condition: New Finish: MIL-STD Manganese Phosphate Country of Origin: USA Troy .875 Low Profile Rifle Gas Block SGAS-875-00BT-00: Compatible with bull barrel rifles that have a 0.875 gas block seat and Armalite 0.308 heavy barrel and other calibers. Machined from 4140 pre-hardened steel. Finished with MIL-STD Manganese Phosphate. Gas tube roll pin not included. Easy installation and solid fit. Limited Lifetime Warranty. Package Contents: Troy .875 Rifle Gas Block SGAS-875-00BT-00 Troy .875 Gas Block