This is the CPD Duramag SS AR-15 6.5 Grendel 10 Round Magazine by C Product Defense. This Duramag magazine holds up to 10 rounds of 6.5 Grendel ammo in its stainless steel body. According to C Products Defense, DURAMAG products are second to none, designed with advanced geometries, and proprietary coatings that easily pass 300-hour salt spray tests.