I love this storage container. It is well made and easy to use. Just unscrew the top and insert tools, tubes, air cartridge, car keys, etc and you are ready to go. My jersey is so much more comfortable now without the weight pulling it down in the back. The container is water proof. The price is very reasonable.
I have seen other brands nearly identical to this for $40 in bike shops, and I doubt they are any lighter or less aero than the Elite Byasi. I've been using this on both my road bike and my MTB, and I am really happy with the clean look so far. I'll have to wait to see how hot this coming summer is when two water bottles is crucial - so if it gets too hot it may be back to the old seat bag.
This storage has lots of space. It easily holds all my tools and repair kits with room leftover. It has an insert where patches or other items cane be stored so you donï¿½t have to empty the whole container to find them.