The Unitron/Polarex rack and pinion focusing mechanisms came in three varieties. The 2.4 inch and 3 inch refractors used the Standard focuser. The friction sleeve held either a 36.2 mm diameter draw tube with eyepiece holder or alternatively, the tubes of accessories such as the Unihex, Duetron, or the Astro-Camera 220.
The Deluxe focuser used on the 3 inch Photo-Equatorial (Model 145) and the 4 inch Altazimuth (Model 150) included locking clamps for both the sleeve and the draw tube to prevent motion during photography.
The 4 inch and larger equatorial models used the Super rack and pinion with its 58mm diameter draw tube to accommodate the wide-field 60mm eyepiece and the Super Unihex. On the photographic models, the Super focuser had a graduated scale to facilitate focus of the camera.
