Camelbak Circuit review: can be used as a vest with small "backpack" for storage because the bladder is completely removable! My old Camelbak was not like this- it was strictly for holding liquids. Interior of vest is an almost fabric mesh- breathable & not abrasive to my most delicate INKnBURN fabrics. (Mind you this was a short hike. Will test on my longer runs as well.) Bottom chest strap is elastic. I see no abrasive wear marks on my shirt. Top chest strap is a heavier nylon fabric but I still see no wear marks on my shirt. 2 front easily accessible/drawstring pockets were good for small handhelds & I didn't even use the front zippered pouch or elastic mesh pouch/pocket. Side stabilizing straps are also made of straps are also made of nylon & have ample room for adjustments. Left or right side option for feeding out the hose from back pack. I'm not completely sold until I take this baby on a few long runs on the trail-- but I suspect it will held up just fine. Life time guarantee doesn't surprise me-- it's well made. I like the colors, too.