Obsidian Arms AR-15 Upper Receiver Vice Block HDPE. Simply secure the assembly into your vise slide the upper onto the block and insert the provided locking pins. Specifications for Obsidian Arms AR-15 Upper Receiver Vice Block: Manufacturer: Obsidian Arms Gun Model: AR-15 Gun Make: AR Platform Gun Type: Rifle Caliber: Universal Fabric/Material: HDPE Color: Yellow Weight: 1.02 lb Condition: New Country of Origin: USA Features of Obsidian Arms AR-15 Upper Receiver Vise Block Fits all standard AR-15 upper receivers High-density polyethylene (HDPE) Locking pins included Package Contents: Obsidian Arms AR-15 Upper Receiver Vise Block What firearm models does the manufacturer say Obsidian Arms AR-15 Upper Receiver Vice Block is compatible with? The manufacturer suggests that Obsidian Arms AR-15 Upper Receiver Vice Block is compatible with AR-15Obsidian Arms OA-VBUA: AR-15 Upper Receiver Vice Block HDPE