I am planning on getting one of these as my first machines, but I am a little confused. From all that I have read the Cibola's are very good. But my question is, are there one or two models of the Cibola? Ron's Dixie Discount metal detectors is listing two models, a Standard model and a High Tone Model. The High tone model is $15.oo more. But no other dealer lists two models. Are there two and if there is, is one better than the other?