This is the Black Dog 'Sonic X' 10 round short profile magazine for AR15 .22 conversions.Manufactured from tough polycarbonate sonically welded together, they are ultra reliable.Compatible with all AR 15 .22s using the common CMMG/Ciener/Atchinson format mechanism, including: Atchison / Ciener conversions Bushmaster C22 CMMG Chiappa DPMS JP rifles Kriss Defiance (works with the Nylon lip type) Lantac Sig Sauer 522 (the branded 522 mags were an early Black Dog design - we recommend the Nylon Lip model for 522s) Spikes Tactical Tactical Solutions Target Master