The California Bottle Tax, also known as the California Redemption Value (CRV), is a fee paid by consumers at the time of purchase on certain types of beverage containers. The CRV fee is typically 5 or 10 cents per container, depending on the size of the container. Consumers can then redeem the containers for cash at designated recycling centers. The 4-pack mentioned in the query likely refers to a pack of four beverage containers that are subject to the CRV fee.