Granberg bar mount clamp on sharpener?

[braggscowboy]

Anyone out there use one of these? I know most of you are like me and just do by hand, but I know I don't get it just the way I want it sometimes.
It is made in Italy and so is Oregon I think. Northern has it on sale right now for 29.99. Cheaper than Oregon and has good reviews. Has anyone use the sthil clamp on? Thanks for any information.

[michiganfarmer]

Ive never used one. I either file the chain on the saw, or take the chain to my shop, and grind it.