TorkMag Inc. specializes in groundbreaking technologies unique to the industry. TorkMag's ultra-durable polymer AR15 magazines use a patented dual spring mechanism that provides increased capacity and reliability-our 35rd mag is the same size as a standard 30. The same principles are applied in our 20rd Glock magazine. The G-Block conversion kit allows standard AR15 lowers to accept 9mm and .40 caliber Glock magazines with no modification to the lower. (less)