Body Wrappers pull-on bra features see-through, adjustable, detachable elastic shoulder straps. Made from totalSTRETCH microfiber, bra is semi-transparent with no side seams. The bra will hug your body like a second skin, making it a perfect choice for underneath your costumes and leotards.
I bought this for my daughter to wear under her competition costumes. I bought a size medium (8-10) and it fits her perfectly. While that's the size she typically wears, it fits tighter on her, which is not typically the case with most child size M sports type bras. She is very skinny, so if you are buying for a girl that is more regular sized or heavy you may want to go up a size. There is a no return policy on this type of undergarment so if it doesn't fit you are out of luck. I shop for my daughter's bathing suits at Justice because the sizes tend to run a little smaller than typical sizes do. I would say the same for this sports bra.
This bra is a pull on style with adjustable, clear plastic straps. I got the large child and it was true to size, fitting my daughter who is in a size 12 clothing perfectly. She didn't want to wear a bra, but after trying it on loved it. She said it was the most comfortable bra she'd ever worn, plus it doesn't show up under her costumes. I would suggest buying packs of extra straps. They tend to tear and get discolored, which you don't want on stage, but they're cheap enough I keep extras on hand.