The Insinkerator 12506 is a #5 Sink Flange Assembly. This durable, easy-to-install stainless steel assembly fits a sink opening of 3-1/2 inches to 4 inches. For extra peace of mind, this sturdy little bud does not require any welding upon installation. This #5 sink flange ensures leak-free operation while your disposer is doing its remarkable performance. It is made for use with the new waste disposers from InSinkErator.