MSD Firewall Feed-Thrus # MSD8211MSD Firewall Feed Thrus # MSD8211 Firewall Feed Thru, Coil Wire, Rynite, Red Black, Male HEI Post, 1. 0 in. Hole Required, Each Firewall Feedthrough Material: Rynite Firewall FeedthroughFinish: Red Black Mounting Hole Size (in): 1. 000 in. Spark Plug Wire Attachment Type: Male post Quantity: Sold individually. MSD designed these firewall feed thrus to prevent voltage leaks in passenger compartment mounted coil applications. Made from Rynite and nylon,