Black Dog Machine's 32 rounds polycarbonate magazine is designed to work with a number of .22LR AR-15 style firearms. Made from durable polycarbonate these magazines feature stainless steel feed lips for improved lifespan. Loading all 32 rounds is also made easier by the built-in thumb pull down tab. (Never use this feature without loading ammo into the magazine. Sliding the thumb assist down the magazine then releasing the thumb assist back to original position will most likely damage the internal pieces. If this happens, the Warranty is voided.) This magazine works with Atchisson/Ciener, CMMG (older models), Model 1 Sales, Spikes Tactical, Tactical Solutions, Target Master Convers Mfg: Black Dog Machine