I have Two extension eyepieces with zooms available. They both have a BNC mount for an eyepiece follower (removable).
One has a built-in eyepiece heater.
I also have available diopters to further the range of the standard diopter adjustment.
I have a 535b for sale.Basic List
535B body
4 x 400, 4x 1000
Video Assist
Steadicam Video top
Ext Eyepiece
other stuff
I am not to sure about pricing, but we can talk.