Gates Diesel Emission Fluid (DEF) Hose Assemblies are specially designed and manufactured to convey Diesel Emission Fluid (DEF). Because DEF freezes at -12°C (+11°F), the hose and couplings are electronically heated using our revolutionary carbon fiber heating system. This patent pending technology allows for more uniform fluid heating compared to heated-wire designs and features thermoplastic over-molds to protect electrical connections against moisture and corrosion. SCR uses Diesel Emissions Fluid (DEF) as a means of converting NOx in engine exhausts into harmless diatomic nitrogen gas and water.