Effortless: If you've ever tried making your own paper spacer rings for a clear lens swap, you know how much of a pain in the butt it can be. Fine Tuning: Having the ability to fine tune the spacing of your lens is crucial in getting a perfectly focused beam pattern. Quality: Nearly identical to the original green o-ring spacers from Koito projectors, our spacers are made of a sturdy, laminated paper material All-Sizes: Available in the most common sizes for both 2.5" and 3" lens swaps, make sure to check the ID/OD's on the lens seat of your projectors to find the right ones. We're glad to make a recommendation too if your dog ate your caliper! Complete: Each set comes with 6 rings, giving you up to .5mm forward adjustment per lens. (which goes a long way, believe it or not).