When i git my fitbit charge 3 it came with the strap and a spare large one. I have been wearing the old strap since i got them last year August. Ny old strap didn’t fit will so i had to make it tight so it can read my heart beat. The more i made it tighter the easier it broke. The new straps are very adjustable and has a lot of holes. And plus it doesn’t slipped through when i sweat. Its so perfect I recommend getting them.