It is a smaller-bore reinforced silicone hose for coolant and heater circuits - the silicone equivalent of rubber heater hose. Two plies of polyester braid give it the pressure rating it needs while keeping it flexible enough to route round a bulkhead or through a tight engine bay. It suits automotive, marine, agricultural and industrial heating and cooling systems.

Inside diameters from 6mm to 25mm, in lengths from 1 metre up to 50 metres, in black, blue and red. Order by inside diameter to match the outside diameter of the spigot it slides onto. Longer lengths are better value per metre, and it is worth buying enough to do both the feed and return in one go.

-30C to +200C and 18 to 24 bar depending on size, built to SAE J20 R3. That is a substantial margin over what a standard cooling system asks of it - a car cooling system typically runs at around 1 to 1.5 bar and well under 120C - which is why silicone hose outlasts the rubber it replaces by so much.

Silicone does not perish, harden or crack with age, heat cycling and ozone exposure. Rubber heater hose has a service life; silicone effectively does not fail from ageing. If the hose is buried behind an engine or runs through a bulkhead where access is poor, spending a little more once is far cheaper than doing the job twice. It also looks considerably better if the run is visible.

Ply count is matched to bore and duty. In these smaller diameters, two plies of polyester braid give ample pressure capability while keeping the hose flexible enough to bend round a tight route - a 4-ply hose in a 10mm bore would be stiff and awkward to install. Our larger radiator hoses step up to 3 and 4 ply where the bore and pressure demand it.

No. This is standard silicone, which is excellent with coolant, water and air but swells and degrades in contact with petrol, diesel and oil. For fuel and oil lines use our fluorosilicone-lined silicone hose, which has an FKM-type inner liner made for hydrocarbons while keeping silicone's heat resistance on the outside.