I bought this last week and took it for its first run today - a 10km run to test out its functionality. Sadly, I am very disappointed with this product. My iPhone (which is in a very slimline case) barely fits into the zippered compartment, and adding a soft flask makes it nearly impossible. I was worried the zip would burst. Carrying a soft flask is a nightmare as I needed to stop my run and remove the entire belt to have a drink. There is absolutely no way I could remove the flask and get it back into the compartment while on the move (or without also removing my phone). Then, once I’d had a drink, the reduced size of my flask meant it kept sliding out of the stretchy bottle compartment. After my flask fell out completely, I gave up and carried it for the remainder of the run. I have loved every single Lululemon product I’ve bought in the last 15 years, however this one has left me feeling very disappointed. The belt is made of high quality materials and it does not bounce, however it is sadly not functional.