You are not going to find any fired hulls marked Cheddite, look at ones that have *** (3) stars on the head. Rio's are Cheddite hulls. You might get a few reloads out of them....maybe. Remington Gun Clubs are your best best. Most Remington hulls are compatible, Nitro, STS and Gun Clubs. I would stay away from the new Remington Field hulls they are a cheaper made hull.
Ballistics Products have Cheddite hulls on sale.
https://www.ballisticproducts.com/12-gauge-2-3_4-hulls/products/104/