For sealed pass-thru of cables wires & fuel lines. Molded of durable vinyl that resists flex fatigue gasoline oil & UV. Boots easily installed with #8 fasteners. 3'' BOOT: Features rigid high-impact non-corrosive plastic reinforcing ring molded into boot for easy mounting & water tight fit. 4'' BOOT: Molded-in tabbed tear-proof slots provide over 2.5'' dia. of open area for cable access without need to split or cut boot. Contoured sides retain shape after installation for water protection.