Forward Controls Design Gas Tube Pin Installation Tool Green GPT Gas tube Pin Tool. That problem is because gas blocks don't have any flat surfaces on them you have to simultaneously hold the block steady hold the pin steady and tap the pin into place. The GPT simplifies this process by fitting over the gas block and retaining the pin so that all you have to do is tap it in. The GPT works with most gas blocks including: Modern Armory Forward Controls Gas Block BCM Rainier VLTOR Knight's Armament Badger Ordnance Daniel Defense SLR and other blocks built to the original Crane Mk12 specification. Forward Controls Gas Tube Pin Tool is also finished in an earth-green tone. This was done purposefully to provide contrast when working on the gas block since most gas blocks are flat. Known incompatible low profile gas blocks: Aero Luth AR and DPMS YHM hinged gas blocks and adjustable gas blocks. Specifications for Forward Controls Design Gas Tube Pin Installation Tool: Manufacturer: Forward Controls Design Color: Green Fabric/Material: 7075 Aluminum Package Contents: Forward Controls Design Gas Tube Pin Installation Tool Forward Controls Design GPT Gas tube Pin Tool: Gas Tube Pin Installation Tool Green