The Davidson Optronics D-275 Autocollimating Alignment Telescope is the workhorse of the Davidson Optronics Alignment Telescope line. This one has been calibrated by the Davidson Optronics Cal Lab, and is ready to go. It is a line of sight telescope with autocollimating abilities. It can be focused from 16" to infinity. A very precise instrument, its optical axis and mechanical axis are parallel within 3 seconds. The D-275 has a 90-degree eyepiece which makes it more convenient to use in tight locations. This is the preferred telescope to use in alignment situations where a reflective optical element is small or otherwise dim. Please inquire if you need a light source. This is a sensitive instrument and out of the last 7 Lightglass Optics has purchased, all have needed major service, so every D-275 we sell will have been Factory Certified and Calibrated by Davidson Optronics. We have one in stock ready to ship, one at Davidson ready to Calibrate and the others ready to ship to Davidson for evaluation and Calibration.