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 Romanian M10/RH10 rifles; a Century Arms proprietary side rail; and even a rear-biased lower for Czech vz. 58s.

• Rear Biased Lower
• Common Usage: AKM Type rifles (Russian, Bulgarian and other AKM pattern rifles)
• Product Dimensions: 4.78 x 0.55 x 2.16 inches
• Weight: 2.88 oz