The diagonal uses an interferometer-tested 1/10th wave first-surface mirror for sharp, distortion-free images. The mirror housing is machined from solid aluminum, rather than simply a flimsy plastic box or a sheet metal stamping, as you’ll find with ordinary diagonals. The solidity of the construction is mirrored in the diagonal’s substantial 17 ounce weight.

The interior of the body is lined with light absorbing foam, in addition to being anodized an antireflective matte black. The 2” focuser-side barrel is also anodized antireflective matte black, and is internally antireflection threaded for even higher contrast. The barrel is threaded to accept standard 2” filters.

Rather than using a metal thumbscrew that contacts eyepiece barrels directly and can scratch them, the diagonal’s 2” eyepiece holder uses a non-marring soft brass compression ring to firmly hold 2” eyepieces and the supplied 1.25” eyepiece adapter. The knurled chrome thumbscrew that operates the compression ring is a full 1/2” in diameter to provide a sure grip in cold weather when wearing gloves or mittens.

The 1.25” eyepiece adapter also uses a compression ring to hold eyepieces in place. The 1.25” adapter is threaded to accept 2” (48mm) filters. It has a slanted groove cut into the outside of its 2” barrel. This engages with the diagonal’s compression ring to act as a safety stop to keep the adapter from accidentally slipping out of the 2” diagonal should the compression ring loosen during use. Dust covers are provided for both the 1.25” adapter and the diagonal’s SCT attachment ring. The diagonal comes in a foam-fitted locking aluminum-frame case for storage and protection.