Pentax Weatherproof XW 3.5mm Extra Wide Eyepiece w/1.25in Barrel

Pentax Weatherproof XW 3.5mm Extra Wide Eyepiece w/1.25in Barrel. These Spotting Scope Accessories by Pentax are built with high-performance high-refraction extra-low-dispersion lanthanum glass elements for crystal clear images and the proprietary multi-layer coatings on all lens surfaces deliver a light transmission efficiency of more than 90 percent over the visible light spectrum. The Pentax XW Multi-Coated Eyepiece is JIS Class 4 weatherproof constructed so you can use your eyepiece in light