A tack bra is a bra insert full of sharp upholstery tacks or thumb tacks. Tacks are pinned onto the bra insert and the sharp edges of the tacks are in direct contact with the wearer. A tack bra is often used in BDSM to further bring a person into submission. It is supposed to bring heightened sensations and awareness of the body while enduring the sharp edges of each tack as the wearer moves.
