A much more comfortable observing position can be achieved with a refractor or catadioptric telescope by using an erecting lens. The beam of light exiting the telescope is deflected by 90° before it enters the eyepiece. In this way, even objects close to the zenith can be observed comfortably.
Erecting lenses are available as zenith mirrors, zenith prisms or Amici prisms. The latter are useful for terrestrial observation and are therefore also available with a flatter deflection angle of 45°.
Most erecting lenses have simple plug-in connectors, as is common seen with eyepieces. For SC telescopes, however, there are also models with screw threads.