AGM Fully Sealed Motorcycle Batteries Listed by Codes or Reference Numbers. The number that's marked on the front of your battery. We only sell batteries that are fully sealed and can be transported safely by our couriers to your doorstep. Batteries are listed by markings on the battery which vary depending on manufacturer. Conventional motorcycle batteries reference numbers usually start with a "C" "or Y" for example but this is only the brand or manufacturers mark. For example: If your battery is marked GTX9-BS, you can use any other battery which will be the same if its only the thee first letter that's different, such as CTX9-BS or YTX9-BS, these are all the same battery. If you're unsure which battery you need, please contact us here and state what markings are on your old battery.