Mishimoto MMHOSE-MIA-90HHBK Mazda Miata Silicone Heater Hose Set, 1990-1991, Black Direct fit for 19901991 Mazda Miata INNER DIAMETER: 0.63" OUTER DIAMETER: 0.94" Maximum Temperature: 330F Constructed with high grade silicone and heat-resistant embedded fibers Mishimoto Lifetime Warranty Interior Material: Heat-resistant embedded fibers Exterior Material: Silicone Maximum Temperature: 330 F Inner Diameter: Hose 1: .63", Hose 2: .63" Outer Diameter: Hose 1: .94", Hose 2: .94"