RYOT4 E.P ROD (Expanded Polyethylene Backer Rod) is a round, flexible, backing rod made of Closed Cell extruded polyethylene foam. It is available in a variety of diameters to fill expansion joints. Backing rod is chemically inert, and resistant to oils, gasoline, and solvents. It does not stain or adhere to sealant materials, acts as a bond-breaker- strip Backer rod is compatible and act as backing with butyl, polysulfide, acrylic, polyurethane, silicone and most other cold applied sealant compositions. Backer Rod Closed Cell is used as a backing rod for horizontal and vertical expansion joints to: • Control the depth of applied sealant. • Act as a barrier interface to prevent three sided adhesion (bond breaker) • Provide a form to assist the sealant in developing the hour glass shape.