FROM THE MANUFACTURER :The actual cup part is thick cotton and has plenty of nipple coverage so you can go braless without worry! The rest is spandex and between the stretch and cling of the spandex and the cross design it like pulls your girls together and pushes them up. I am really not sure what the secret is here but it does indeed push you up and makes you look a full cup size bigger. I think the magic is that a pushup would only lift and this lifts and pulls together. So that might be why is better than a push-up. I’m in the pictures braless in one pic and with a bra in another and I’m a 32C.