bals mk1 bean bag.

I had one for a while because I thought it'd be great to have a rear bag with the gun all the time and it was mighty convenient. The construction of the bag was first rate, I think they had Eagle Industries making them so it was practically bomb proof. The extra weight at the rear also helped balance out my rifle for offhand or sling supported shooting. SKD has always been great to order from in my experience so there shouldn't be any concerns there. I ended up selling mine though because the bag was a bit too small for me so I ended up making my own rear bag.
 
I have one, after a slight modification I love it, skd transaction was really smooth. I felt mine was underfilled, so I cut it open and replaced the filling with airsoft bbs- its light and really good now. Always on my rifle.