M110 SASS. Fits SR-25 and AR style rifles. Adjustable for length of pull without tools. Metal buttpad and internals for strength. Bottom swivel mount can be set to left side, bottom, or right side and will accept standard hunting/precision sling swivels. Includes front HD push button socket on left and right side, HD Push Button shown sold separately. M16A1 buttstock screw required for installation, included with buttstock. Buffer/tube/spring sold separately, they can be found under the related products tab.