The 3rd generation models represent the latest ToneRite models which can be used equally on steel or nylon string acoustics, as well as archtops and hollowbodies.
According to the company, some of the improvements of the 3rd generation are:
The ToneRite electronics have now been updated. This update allows for finer control over intensity and harmonic content.
New Elastone feet. These feet are designed to not only fit better, but also improve the energy transfer from the ToneRite to your instrument.
You can now use this single model of the ToneRite on steel string and nylon string acoustics as well as archtops and hollowbodies.
Works on Electric guitars as well.
An initial ToneRite treatment of 72-144 hours is recommended. Subsequent treatments might be required to maintain and further develop your instrument. The ToneRite is not designed to make a poor instrument great.
Pricing and Availability
ToneRite is offering a price promotion for this month of $149 instead of $186.25.
For more info see ToneRite.