Replacement butt pads are round-shaped pads worn in a specialized panty with pockets in the back to hold the pads in place (known as a "pocket-panty"). It's important to note that all these inserts are designed to be worn inside a pocket-panty and can not be used inside a regular pair of undies as they will likely move around (or even fall out). Round-shaped pads are intended for use as butt pads to add curves and confidence over the booty cheeks. Looking for a different shape? Check out this collection of Booty/Hip Pads.