West System 404 High Density Filler This high density filler by West System is designed to act as an epoxy thickening agent. Created for maximum adhesion properties in hardware bonding where high-cyclic loads are anticipated. Also useful for filleting or gap filling with epoxy where maximum strength is needed. Excellent at bonding hardware with epoxy to increase the maximum strength and load capacity. Excellent strong and structural gap filler. Available in an off white color. West Systems 404 H