The version for the 1.8..no idea on the version, had it about 8 years. It's too big for the 1.2..but the same design as the 1.2 version that is on the SSS/Primesat website.
If you go on the Primesat website it mentions MK4 but the pictures are from 2012 that probably is a copyright date only..I have this polar mount for the 1.8 I think any changes if any, were minimal and the design is still the same. Have you rang SSS to see what the differences are?