Finally a top-quality astronomical accessory at affordable price! William Optics Binoviewer package besides to guarantee an exceptional bright optical field, it's a complete and rich product, accurate in every its detail. The optical scheme which includes a Bak prisma allows you a very clear and sharp view. I've used it with a Smidth Cassegrain telescope and with a small APO refractor having both amazing results! Best recommend for visual observations, especially for solar system objects (just take a look at Jupiter or Moon!)! Safe transport and fast delivery time! Very Good!