I have previously used Guardian Gears Shark mini non-magnetic tank bag, and bought this when I upgraded my bike with a metal tank. It's a perfect sized tank bag to store all your quick access items like phone, wallet, water bottle, rain gears, cables and chargers. The magnets are strong and the bag never moved even at triple digit speeds. I put it with the sloped side towards the seat, and it helps me support my knees when I saddle stand.
The see-through rain cover is something I missed on my previous one, although now I use an android auto setup and don't need to look at my phone display for navigation.
My only complain with this bag is that it missed the double straps to wear it on your back. It gets a sling-bag style single strap which is very uncomfortable. The Fly model has it, but it was too big for my needs.