yes, it attaches to the D’s and the billets so it doesn’t move - the D attachment even lifts it off the withers a bit so it’s presumably less irritating to the horse - it attaches more to the saddle than lays on the horse, if that makes sense?. I just try to not fill up the top pocket so there isn’t a lot of bulk below my hands, then the flask and water bottle go in the other two pockets.
And best thing ever? It has a little neoprene loop that holds a tube of chapstick perfectly. I get a slightly thicker tube and the top is wedged in perfectly, just take out the stick, apply and put it back in the cap. That thing has been a lifesaver… 'Scuse me, a lipsaver! 