The OTA is an unusual but proven design. Very solidly built, it is in fact two concentric tubes, with the inner tube sliding forward and backward to achieve focus. The outer is steel with primed and painted. I believe the inner tube is a magnesium alloy with 3 knife edge baffles and the famous Zeiss 63/840 objective and cell.
On the outside the OTA has gun sights for aiming, dovetail (slightly narrower than a standard Vixen) and focus knob.