I played with Big Bite after recieving it and reading the very brief instructions.....
I am a (woman) contractor who is not a stranger to various tools but this one you really have to look at and play withto catch on to the the rotating heads for the various sized grommets. The diameter sizing system is in a great location on the top side ...
All I can say is dont be afraid to play with it and experiment.....
If you can use a die cut system, either electric or manual you can master this in a few moments.
C`Est Bon