The M4-ZAS P SB Shock Absorbing Buttstock replaces the original Zastava stock with an M4 style collapsible and side folding stock with a built in shock absorbing mechanism. Advantages: Non slip Buttpad design for superior shoulder positioning and tactical performance Integrated long lasting shock absorbing mechanism improves rapid fire accuracy Water proof anti rattle storage compartment for two CR123 or AA batteries After market sized 6061 hard anodized aluminum buffer tube Integrated quick detach sling swivel connectors on both sides Locking is released by the push of a button Spring lock on folded position, opens by a simple pulling motion and locks Left folding stock by default Available in black, olive drab green, or desert tanCompatibility: Zastava (Yugo) M70 B1, B3 / M77 B1 Models.