Reuse Your Ballasts: These will save you some money and allow the use of AMP-connected (aftermarket) bulbs with your aftermarket or OEM D2S HID ballasts. Works with 99% of D2S HD ballasts that have "D2S" outputs excluding any with external igniters like the Matsushita ballasts. Please confirm compatibility by checking the product pictures if unsure. Industry Standard: These are built to industry standard specifications for AMP male/female high-voltage outputs, and "D2S" bulbs. They should work with all OEM and aftermarket ballasts and bulbs. Added Length: Another benefit of using these that many don't realize is that they instantly add length to the output on your ballast - giving you a bit more freedom to choose where things are mounted. We'll take it! Well-made: These are properly insulated from top to bottom to shield the high-voltage that HID ballasts produced. Thick rubber insulation prevents wires from getting nicked, and voltage from leaking out. Don't want any of that business around here! In Comparison: There are a lot of these adapters on the market, you can find something seemingly the same on eBay or Amazon for probably a couple bucks less (we know, because we used to carry the cheaper ones too) - but take it from us, its not worth it. They may cause bulb ignition reliability problems, or even worse, fry the base of your bulbs from poor tolerances. Though still inexpensive, our adapters are top quality!