This unit is a fixed stock. It pairs best with a pistol buffer tube but you can also use a carbine buffer tube. This unit was designed was to comply with various state laws regarding the use of pistol grips. Check with your attorney to see if this unit is compliant in your area. Thoughtfully designed this stock has a built in QD point and rubber buttpad for less felt recoil. When combined with a bipod it meant to be self leveling. Overall length of 13.75". Polymer construction with steel QD point.