The MagPul PTS UBR Stock is a revolutionary adjustable stock that offers the same stability as a full stock. Even full adjusted this stock is solid, no wobbling or shifting like other retractable stocks. In addition to its unrivaled foundation it features a small storage space for miscellaneous items, and 4 QD sling swivel mounts. Magpul has made an excellent reputation for themselves as one of the first real gun manufacturers to embrace airsoft; and since this is the airsoft version of the UBR stock , it comes with the necessary hardware to mount onto your M4/M16 AEG, and the buffer tube is made for battery storage. Add killer looks to your M4/M16 while maintaining a clean look by hiding the battery.