At Lunt telescopes, there are a number of variants with different options. It is possible to find out which model is being offered by looking at the designation.
An important criterion, also reflected in the price, is the size of the blocking filter. There are 3 different blocking filter sizes: 6mm, 12mm and 18mm in diameter. The designations for these are B600, B1200 and B1800 respectively. If there is nothing in the title, then it is an OTA without a blocking filter!
CaK or Ha mean that the instrument has been optimized for the blue calcium line or the red H-alpha line. Over 90% of instruments sold are H-alpha instruments, with the designation Ha.
C or FT refer to the two different focuser versions. C means the standard focuser and FT means an improved model from FeatherTouch.
PT is the designation for instruments with fine tuning that uses air pressure. Non-PT filters have fine tuning that works by tilting. The air pressure version usually provides a somewhat more homogeneous field.
DS or DS50 is the term for a 'double stack'. These instruments have two Etalon filters. This achieves a tighter bandwidth and therefore better contrast.
In addition, you can find 2 numbers in the title separated by a slash. The first number indicates the diameter of the front lens. The second number is the focal length. So a 60/500 telescope would have a 60mm aperture and a focal length of 500mm. The lens diameter is usually also the diameter of the Etalon supplied.
