Plus Ultra's Biodegradable Electric Toothbrush Replacement Heads are made with cornstarch and soft nylon bristles. The soft nylon bristles are designed to treat hard to reach areas of the mouth as well provide gentle gum cleaning. Reduce plastic waste and elevate your bathroom aesthetic with the 3PK biodegradable replacement heads that are compostable in any municiple compost facility. These replacement heads are compatible with Philips Sonicare click-on-handles electric base.