Sierra Shields Nautiflex Corrugated Silicone Exhaust Hose 3-12 The Nautiflex Corrugated Silicone Exhaust 3-12 Hose two ply construction, has wire captured between fabric plies. The hose features a blue silicone tube and cover with a smooth finish for easy cleaning. It also features wire reinforced that will not collapse under suction or in a bend. The corrugated cover allows the hose to bend for easy installation. Specifications Wt. C 227 I.D. 3 12 or 90mm O.D. 4 1964 or 109mm Bend Radius 4 x I.