So I had an idea for weight training with a UTE. I took a wood pellet bag(40lbs) and wrapped it in Duct Tape. I formed it while taping to get it near the 12 x 7 size of the UTE. I can now add this and maybe a 10lb plate or 25# shot bag and have 40, 50 and 65 lbs to train with. Either way. It fills out the pack nice, much differently than a lead shot bag pulling down the bottom on your rear.