Bowbo - it has a stop plate on the shaft so you don't stick it in too far... apparently there were some owners of the original that didn't think about stopping at the T-handle...
I don't have one, but am working on a prototype that does the same thing, only automatically ties off the canal and cuts it... initial model will have a squeeze handle, manual option... will sell for $19.95
Model II will be automatic, electrically powered from a rechargeable DC battery, with status LED lights, and a small audio chip, which will play "Love Me Tender"... will sell for $79.95
