Solid lower extension and recoil kit - Griffin Armament Griffin Stock Mounting Kit

I purchased because I wanted to try the SOB weight on a GA MK-2 lower receiver, for a 10.3" 5.56 upper. I wanted to see how it compared to the kynshot. I also needed an endplate and receiver extension, so this kit made sense. There is nothing special about the tube, spring, nut or plate. It would be nice if they had an offering for a blue spring, but they don't so, whatever.