Review on LEZYNE Caddy QR Rail Mount Bike Saddle Bag - Compact, Water Resistant, Bicycle Seat Bag by Travis Carter

The size of the bag fits what I carry. A tube, 19 crank, multi-tool, tire levers, tire patch kit. The multi-tool fits in an outside pocket. There is no room for anything else, phone, wallet etc. The base that comes on the rails is the biggest complaint, it's too short. I had to slide the saddle back to attach the mount. I didn't use a light harness because. My Fizik saddle has a saddle mount. It's too early to tell if it will hold up, but so far so good, no rattling or loose zippers.