BV Bicycle Strap-On Saddle Bag - Waterproof Cycling Seat Bag with Reflective Strip for Night Safety | Perfect Size Bike Storage for Phone, Keys & Tools | Ideal for Road Bikes, Mountain Bikes & Commuting

I got the medium size. It seems to have good materials and good stitching. The main strap and buck are pretty tough and I like the way the strap clips and can be cinched really tight so the bag doesn't wobble at all. The seat tube strap could be better. Its fine for thick tubes, but for thinner ones its tough to cinch it very tight. I had to snake it around a bit to work with my post.The capacity is great for carrying tools and a tube. My pics show a 27.5 tube in it with it unexpanded and expanded. I also like the little clip to keep something like a key from readily falling out when you open it.