In general, there are 2 popular sizes of grips: Those that fit a 7/8" diameter handlebar and those for a 1" handlebar.
So, you have to know which size you have.
Measure the left one because the right one has the throttle sleeve on it.
The pair of grips are designed to fit both handlebar ends even thought the two are not the same size.
If you haven't a way to measure the handlebar than use a supplier that knows the info for the scooter you have.
JC Whitney is not our favorite supplier.
You might try
http://www.racingplanetusa.com/styling-parts-c-2_36_274-1.html?sessID=b43ec99eabd3c95c9a374eadaad43eaeIf you provide the brand and model scooter in your forum entry, some member will be able to help.
Scoot safely,