---Please read everything--- -This is our custom variable speed mx125 12-20 kit- This ad is for the "controller and throttle kit only" as pictured in the first main picture and does NOT include the mx125 bike itself or the headlights, taillights, brake lights ,speed reducer, batteries or any of the other optional items you can purchase separately from us. Please take note we have all the different throttles available pictured above, it comes standard with the throttle in main picture (half twist with on off key), if you want ANY other throttle you must send a note to seller at checkout and then click 'AD" after you type it or it dont get sent with order..simply include the # in the picture of the throttle you see! The 4 and 5 led lights do not read properly in 12v,18, or 20v so we do not picture them. IF you want the 24volt kit to overvolt the 12v motor and go 50% faster its item number 226010673580 but it will no longer run in 12v and requires 24v lithium or another 12v put in series and one of our 24volt chargers and charger ports. We did it again! The very first variable speed kit on the market specific plug n play for ALL versions of the razor mx125. This kit you can use the factory 12v battery and you can find 3d printed battery holders on ebay for your milwalkee 18v battery and your 20v dewalt battery which works even better and makes it faster, we send the connector and pins to attach to the battery holder just incase you go that way. Here's the best part of this kit---No more of the full throttle on off which is unsafe and dont make sense, this gives your child full throttle control from slow to fast and everything in between and with the half twist it reads exact voltage and gives you a key and a spare key so you can make sure they dont ride without you there. (the half twist takes hits better if dropped and the thumb throttles do not come with grips) With this kit you can also ad a speed reducer so you can control the top speed of it because we all buy our kids stuff the wife dont want us to at too young of a age and the reducer will allow you to turn it down to go as slow as you feel is safe! Here are some other items that work with this kit that are plug n play Headlight kit- eBay item number: 222627137235 Brake or taillight kit (requires 2 kits for both)- eBay item number: 324198103238 (installed pics in listing) Reduce top speed with our hidden speed reducer setup- eBay item number: 222627137275 (installed pics in listing) Remember If you would like any other style throttle we sell (as pictured above) we can swap it, include that note and a message directly after incase the note didnt go threw.. Detailed step by step directions included.. --This kit only fits the 12volt mx125-- We also sell a 24v kit for it if you want to modify it to fit 2 12v batteries or 2 of the milwalkee 12v in series as pictured in last picture in this listing. and it will be 50% faster and will require a 24v charger and charger port if you use sla, agm or gel.. Here is the item number for the 24v charger and 3 pin charger port--322690569686 You could swap the motor to a e100 motor thats 24v and buy our 36v kit and run 2 of the 18v milwalkee batteries in series or 2 of the dewalt 20v in series or a 40v ryobi threw it but thats your call