This listing includes one brand new high performance adjustable racing 12v DC CDI box! Fits: Hammerhead Twister GTS GT SS GL LT 150 150CC Go Kart. Function: These will eliminate that irritating rev-limiter that is keeping you restricted! This will also re-set your ignition advance curve for better acceleration. Reliable and durable than the standard units Adjustable from 15 to 20. These are DC fired CDI to boost performance ( Will not work on AC Powered Scooters) How to find out if your scooter is AC or DC? In general, the DC CDI's tend to be larger in size than the AC ones. Another test is if the headlights turn on without the engine running, (with just the key on), it is a DC system. In the AC system the headlight requires the engine to be running. Another indication is, if the engine will only run with a battery it is DC. If it will run without a battery, it is a AC system. Package includes: 1 X DC CDI (plug size 1 1/4 INCH x 13/16 Inch). Payment: Shipping and Handling: FREE USPS First Class Shipping We ship only in USA,ship to address provided by PAYPAL only. Items will be shipped out within 24 hours after payment cleared VIA USPS first class mail North Carolina residents pay a sales tax of 7% Return / Refund Return is accepted within 14 days after the buyer's receiving the item. If this item is defective upon receipt, customer has up to 14 days from date of receipt for exchange of a new one. Include your name, address, item, daytime telephone, how you paid, and if you are requesting a refund or exchange. After getting the returned item, we will refund the customer at the item's price ( excluding the shipping costs to and from).