HPS 5/16" (8.0mm) 4-ply High Temp 3 Feet Straight Coupler Tube Silicone Hose Blue Temperature Range:- 65 deg. F to + 350 deg. F (177 deg. C) Reinforced Layer: 4-ply Hose Inside Diameter: 5/16" (8mm), Hose Outside Diameter: 0.71" (18mm) Wall Thickness: 5mm, Color: Blue Silicone hose is compatible with water or anti-freeze such as coolant.Silicone hose is NOT compatible with fuel or oil.