More from Amazon.com : http://www.amazon.com/gp/product/B000FA8U9S?tag=purrfectcatdi-20

Orion 8880 1.25-Inch Dielectric Mirror Star Diagonal

90 diagonal features sophisticated lab-tested dielectric coatings that boast an astounding 99 percent reflectivity
Dielectric mirror coatings are more durable and more reflective than enhanced aluminum coatings
Diagonal provides a comfortable 90-degree viewing orientation when observing the night sky through a refractor Maksutov-Cassegrain Mak-Cass or Schmidt-Cassegrain telescope
Machined and anodized aluminum housing features machine-threaded baffles for optimized contrast
125 nosepiece barrel is threaded to accept like-sized Orion eyepiece filters