I have this Stribog brace/stalk Would like to sell. It functions great.  I have never firedthe Stribog,  just set it up. Now that I have a form 4 for it I have been  getting it ready to go. This takes a Gear Head tailhook or a stock so you can go either way. The prices is minus the Haga Defense stalk It was $135. I can make you a really good deal on the butt stock.
$75 add to the price for it. Asking$250 $200 shipped. Again without the stalk. This is an original Grand Powers part so fit and finish are great. Any questions just ask.

(update)

I just looked on the web and this Grand Power Stribog Factory PDW Tailhook Adapter UPC: 8588005944212
Dose not have 5 positions. It collapses nicely but extends all the way out to 10.5". Just not trying to hide anything.