UTG Pro AR15 6-position Receiver Extension Tube Mil-spec Matte Black. Finished in a Matte Black Type III Class 2 Hard Coat Anodize with a Dry Film Lube Coated Interior Specifications for UTG Pro AR15 6-position Receiver Extension Tube: Manufacturer: UTG Pro Finish: Matte Anodized Fabric/Material: 7075-T6 Aluminum Gun Make: AR Platform Gun Model: AR-15 Gun Type: Handgun Length: 7.25 in Condition: New Weight: 4 oz Package Contents: UTG Pro AR15 6-position Receiver Extension Tube What firearm models does the manufacturer say UTG Pro AR15 6-position Receiver Extension Tube is compatible with? The manufacturer suggests that UTG Pro AR15 6-position Receiver Extension Tube is compatible with AR-15UTG Pro TLU001: Buffer Tube Ar-15 Mil-spec 6-position