Keep flame and heat out of the driver's compartment by sealing the holes in your firewall where hoses or wire harnesses pass through. These grommet seals have a large diameter rubber insert bonded to a metal ring. The rubber can stretch a bit to allow hose ends or small wire harness plugs to pass through so you don't have to disassemble everything. The 3.0" OD, 0.040" thick metal ring has four 1/8" diameter holes on a 2 5/8" circle for easy mounting. Sold individually. The size shown is the inside diameter (unstretched) of the rubber grommet.