Konus XTC-30 Scope Lens Reducer White Oak Lens Reducer assembly for the Konus XTC-30 Rifle Scope or any scope that uses a Butler Creek #18 lens cover White Oak's unique "ghost ring" design is a transparent lens with a chamfer around the center hole. The lens is transparent which allows a full field of view so you can still see surrounding targets and target numbers but acts as a ghost ring centering your eye in the hole. The lens is held in place by a Butler Creek lens cap (eye #18). To Install - Simply press the lens into the lens cap until it is against the shoulder inside the cap. It will be a snug fit, the snug fit ensures the hole is centered. Then install the lens cap on your scope as usual. Lenses should be cleaned with gentle soap and water using a soft cloth. DO NOT use ammonia based glass cleaners. tle soap and water using a soft cloth. DO NOT use ammonia-based glass cleaners.