What's so special about sentinal pro dongle

[Mike]

I am starting to get curious.   Out of all my machines the one I get the most 
requests for is the sentinal pro dongle. 

Is there a pending patent case?
Is the software that required these still in use or demand?

this one is labelled 

1294/6558
C.B. Microtek ltd
-----------------------------------
4F33BH-B
9451L52135

-- 
Collector of vintage computers http://www.ncf.ca/~ba600