Fits my 48v 21Ah 13S6P battery in the pocket with ease. Very comfortable using the wide hip strap to take the weight of the battery off the shoulders. Keep nutritionals in the hip pocket for ease of use while riding. The bag is well made with lots of room an options yet adjustable and snug enough to not wander. Rode 118 miles of trail… that day was 9.5 hours of saddle time with a 12LB spare battery - no back or shoulder issues…. just an awesome ride. Only time I really noticed the pack was when taking it off or putting it on…. Set and forget. Best long distance ebike pack out there plus back protection. Win win.