The 8" Diameter Superior Firestop Thimble For Penetrating Joist is a valuable accessory to your new fireplace system. A firestop provides additional protection at points where the chimney passes through combustible materials, and the thimble assists this key component. It is designed for penetrating the joist and getting the firestop up and running. Avoid harmful damages that can occur with combustible materials and fire, and simply enjoy your next family even with a warm, safe fire.

Features:

• Heavy duty material and 8" diameter
• Single pack for penetrating joist
• Assists firestop with safety