Choose the top flow hole diameter from the sales drop down list. This size is an actual mm measurement of the diameter of the hole itself and usually is stamped on the end of the seat. If converting from gravity feed fuel to pumped, down sizing this hole size eliminates the risk of seat pop off and flooding.
Some seats may not be found in our listings and these will only be available from the OEM motorcycle manufacturer for whom they will have been specially made. If unsure call or email.