While both the UBR(R) and STR(R) 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(R), MOE(R) Rifle, MOE(R) Fixed Carbine, MOE(R) 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.