Bra inserts are also known as cookies or bra padding. Silicone ones are sometimes called chicken fillets due to their resemblance to them. Often they are promoted as a non-surgical option to increase your bra size. As well as giving you the appearance of larger breasts they can be worn with a push-up bra to increase cleavage.
They sit in the bottom of the bra cups to push your breasts up and fill out the bra. They come in a variety of sizes and shapes and are usually made from foam or silicone rubber, some are liquid or gel filled. The silicone ones will mold to your shape and grip against your skin better than a fabric and foam one will. If you are worried about them coming out, these are a better option. Some bras will have pockets for adding padding built into them, that’s another way to keep them from slipping out.
Another great use for them is to balance out your breast size during your cycle. A lot of women will have their breast size change quite significantly through different phases of their cycle, if you don’t want to have to buy different bras for when you are smaller then use these instead.
You may need to go up a cup size (or even two) if you use them. Make sure you take them with you when you are choosing a bra if you intend to wear them with it.
You can buy them in most lingerie stores or online on websites including Amazon.