BLACKHAWK! Adjustable AR-15 and M4 Buttstock, 5-Position, Mil-Spec Tube, Desert Tan: * Durable, reinforced polymer construction * Precision fit for quick and smooth length adjustment * Designed for comfortable cheek weld * Ambidextrous sling mounting locations with pre-installed 1" quick-detach sling swivel * Different models available to fit commercial and military-sized carbine tubes * Measure rear tube diameter to determine fit: commercial 1.170" or mil-spec 1.146" * Limited lifetime warranty * K11020-C