Porcelynne Black Plastic Bra/Headband Replacement Strap Slides with Gripping Teeth - 1/2" or 13mm Opening - 10 Pairs Black plastic sliders with teeth that measure 1/2" or 13mm on the interior and are in the shape of an 8. Check the seller's other products for ring and hooks. Each pair contains 2 pieces. Used on bra straps, tank top straps and headbands. Bra/Headband strap hardware ideal for replacement parts or custom bra making. Can be used to make adjustable straps of any kind.