Check the listing for details. Razor - throttle, controller, Variable Speed Kit - SAFETY SPEED CONTROL AD ON. Condition: New. Listed at 20.00 USD. This is not available from Razor and will not fit on a standard razor scooter,go cart or mx series without the use of our varible speed kits found online and in our ebay store--Your scooter must have a variable speed in order to control it.. This is a must have and a good way to keep your kids safe and allow smaller kids to use the scooter..With the 360 degree turn of a heavy duty aluminum knob you can control how fast your scooter can go EVEN when the throttle is wide open! You can go from barely moving to full throttle and everything in between,it works sorta like a dimmer switch on your lights in your house,you can mount it anywhere you like by simply drilling a hole and sliding it threw and tighten the nut (we also have a mountable box version available in our ebay store along with LED headlight kits,Tailight kits,Brake light kits and more!If your smaller child wants to drive your bigger childs scooter,go kart,drifter,mx or dirt quads..now they can with this installed! Works with 24v,36v and 48v units with variable speed only.. Fits all (all versions) scooters that have installed our variable speed kits.. COMES WITH DIRECTIONS AND PHONE SUPPORT EVEN ON HOLIDAYS-This is a safety feature that you simply remove the wire,mentioned in the directions,from your existing throttle connector and slide it into the female end of the reducer then slide the male end of the reducer into the spot you removed the other wire from (really easy trust me)..then mount the reducer or hide it where you see fit..the knob slides off and it comes with a mounting nut. If you order this at the same time as the variable speed kit we leave out the wire you need and pack it together and ship priority!Kit includes: 1- Fast Scooters Speed Safety Control - We have both silver and black knobs2- Heat shrink and directions - comes with about a foot of wire,if you need more just send a note at checkout.