In 2012, RS Regulate began rolling out the first models of the AK-300 Modular Side Mount System, which now features six fully modular uppers and nine different lowers: a front-biased, a rear-biased, and a full-length lower for most Eastern European AK side rails; a front-biased and full-length lower for Yugo/Serbian rifles; a PSL and and Romanian M10/RH10 rifles; a Century Arms proprietary side rail; and even a rear-biased lower for Czech vz. 58s.Features:Front Biased LowerCommon Usage: AKM Type rifles (Russian, Bulgarian and other AKM pattern rifles)Product Dimensions: 5.87 x 0.55 x 2.16 inchesWeight: 2.88 oz