After going cheap and purchasing (and returning) aZeikos ZE-UV52 52mm Multi-Coated UV Filter, I decided to go to the other end of scale and purchase this filter. The difference is like night and day.I don't have access to an optical bench to make any real measurements, but it's obvious from just looking that the multi-coating on this filter works well. Reflections are significantly reduced and the filter is water clear. The edge of the glass is coated black to eliminate any internal reflection from the edge.Physically, the black aluminum is knurled on the side to make the filter easy to remove from a lens...stuck filters with smooth sides can be a real pain.The Hoya PRO1 filters are a bit pricey, but worth every penny. They're exactly what a filter should be. Highly recommended.