IF THE BOOT BETWEEN THE CARB AND THE AIR FILTER BOX IS BAD THIS IS THE ONLY WAY TO GET A NEW BOOT. THIS FITS THE CT90 K1 ONLY. 39B @ SPACER CARB INLET OPENING EXTENDER FITS 30MM TO 37MM OD CARB MOUTH'S 1/17P (CARB/ADP/EXT) (S1383)MADE OF GAS RESISTANT RUBBER, THIS WILL EXTEND AND OR ENLARGE THE CARB MOUTH ON CARBS OF APPROX 33MM TO 37MM REAR OPENINGS/MOUTHS CARB/ADP/EXT (S1383)