Astromania's 2" mirror diagonal is an excellent alternative to higher priced diagonals for those on a budget or just getting started in the 2" format. The 2" diagonal features dielectric coatings with 93% reflectivity across the visible spectrum and a 1/10 wave mirror. The all metal diagonal body is CNC machined. The combined result is a superb diagonal offering excellent mechanical and optical quality at a great price. Star diagonal is the term commonly associated with 90°mirror diagonals such as this, which let you view objects that are at a 90°angle from the direction the telescope is pointing. This allows quite comfortable viewing when the telescope is at or near the zenith. Upgrading your diagonal and switching to 2" eyepieces is one of the best investments you can make in your telescope. The wider diagonal captures more of the telescope's light cone, perfect for viewing faint, deep sky objects like nebulae and galaxies.