I use it thrice a week (and the other same exact product but in red color) when running both on the treadmill and outside on track after working out every day. It's comfortable and helps you sweat little more than without it on. I got a large and it fits (not too large or too small) I have a body that time by time change from medium to large and vice versa. It actually depends on the clothing materials and such though, but anyway.

Great product.