Mk3 DEVICE "LITE" Introducing the Mk3 DEVICE "LITE". The Mk3 is the little brother to the Mk1 DEVICE Upper Receiver Fixture. The Mk3 retains the same operating principal of the Mk1 in a smaller, lighter leaner platform. The Mk3 weighs in at 1.7 pounds of machined 6061-T6 Aluminum with a Type III hard coat anodized finish. The Mk3 also features a full length "T" slot on the bases bottom compatible with M-LOK T-nuts. This feature can allow M-LOK accessories, such as Pic Rail sections, to be applied for scope set-up and repair. Or this "T" slot can be utilized as a set-up jig for assembly and timing of any M-LOK compatible accessories. Mfg: The Device Manufacturing.