Hydrobats are made of Hydrostone plaster making them more durable than regular plaster bats. All Hydrobats are casted with two rubber grommets that won't wear out and keep a tight grip over bat pins. Hydrobats are designed to absorb moisture from your pots allowing you to release your work without the use of a wire cutter. So go ahead and start making that dinner plate set you've been putting off --you'll never wire cut through the bottom of a piece again.