Design Engineering Vapor Block solves the problem of fuel and other fluids boiling from extreme heat and causing a vapor lock situation. Prevent rough idling and difficult starting caused by vapor lock with DEI Vapor Block. Vapor Block fuel line sleeve was specifically developed to prevent vapor lock in fuel systems by greatly reducing heat in the line to keep fuel cooler and below boiling. Vapor Block installs easily with a split design and adhesive flap. There is no need to disconnect the fuel line to install. Simply wrap Vapor Block around the line, remove the adhesive liner and press the adhesive flap into place. Made of glass fiber and polyester laminated to an aluminum outer layer, Vapor Block offers excellent long lasting thermal protection without paying for expensive repairs or modifications.