While both the UBR and STR come with TYPE 1 push-button QD swivel sockets pre-installed on the left side of the stock, this Sling Mount Kit – TYPE 2 can be installed on the opposite side to add additional push-button QD Sling Swivels or our own Magpul(R) QDM. Additionally, for running ambidextrous sling swivels on the SGA, MOE Rifle, MOE Fixed Carbine, MOE AK, Zhukov-S, Hunter 700″ and Hunter X-22 Stocks, this TYPE 2 Kit must be utilized in conjunction with the optional TYPE 1 Kit. Heavy-duty black phosphatized steel construction easily installs with the UBR or STR’s original hardware, or with the hardware included with the TYPE 1 Kit. Swivels not included.