Black Dog Machine is an industry leader in durable polymer magazines for AR-15 conversions. The 3rd generation features steel feed lips and a thumb pull down for easy loading. For use with the specified conversion only. Note:Compatible with the Following AR-15 Rimfire Conversions or Dedicated Firearms: Atchisson Ciener CMMG Model 1 Sales Spike's Tactical Tactical Solutions Target Master Kel-Tec PLR-22 Does not work with: ColtDPMSS&W MP 15-22SIG 522