I think these are relatively new from Arisaka Defense, some info popped up on a defense industry news page I like to check out and I thought some guys here might be interested. I'm getting started on a review of this set up that's designed for the Magpul SL and SL-S stocks. I have both stocks and while excellent options, I found them lacking on my SPR and Recce, which these products seem to address. Hoping to get some range time with them over the Christmas break and try them out.