Tacmod US Tactical Systems Back-Up 20 AR Stock Assembly Kit Black. These AR15 Stocks from US Tactical Systems work with M16A1 or AR-15 platforms and let you install the stock in the same manner as a standard A2. The US Tactical Systems Backup 20 AR Stock Assembly Set is built to last which is why they are constructed from Dupont Zytel. You can install this US Tactical Systems Backup 20 Stock Assembly on an AR-15 or M16 platform and it works on both M16A2 or AR-15 platforms. However please note that this kit is only for the US Tactical Systems Back-Up 20 Material Stock Assembly Kit for M16 and AR-15. Specifications for Tacmod US Tactical Systems Back-Up 20 AR Stock Assembly Kit: Manufacturer: Tacmod Color: Black Stock/Brace Material: Steel Gun Model: M16A1 M16 AR-15 Gun Make: AR Platform Gun Type: Rifle Fabric/Material: Steel Package Contents: Tacmod US Tactical Systems Back-Up 20 AR Stock Assembly Kit What firearm models does the manufacturer say Tacmod US Tactical Systems Back-Up 20 AR Stock Assembly Kit is compatible with? The manufacturer says that Tacmod US Tactical Systems Back-Up 20 AR Stock Assembly Kit is compatible with AR-15 M16 M16A1Tacmod 660-754: US Tactical Systems Back-Up 20 AR Stock Assembly Kit Black