The original factory tyre on Inokim Light 1 was 8½x2 (50-134). Light 2 originally had Inokim branded nameplate 8½x2 (50-139) and subsequently transitioned to the non-Inokim branded CST 8.5x2.00-5.5 [C9343] which has 135mm internal diameter. My Mobelity suggest this tube is also suitable for both Inokim Light 1 and 2.