This is either a W.O. or an Apogee crayford focuser... not sure which. Purchased from OPT. It works and looks great. Threads directly onto Meade SCT OTA's (7-10 inch I know for sure) and I also beleive it threads on to other SCT's. I have upgraded to a motorized JMI is reason for selling. $90.00 plus $7.00 shipping in CONUS. Thanks for looking.