6mm (approx. 1/4") inside diameter. Industrial reinforced quality fuel / oil line hose. Compatible with gasoline and oils. Resists swelling. Comes with the OEM outside diameter. Sold in 25 ft. (7.5 meter) rolls. OEM replacement reference 63501-68B. Supersedes 62349-99, 63501-68A, 63510-04A, 63518-04A.