Classic 70 G3 EXP & Single Dog
The Classic 70 is a simple and effective way to get your training message across. Perfect for solving behavior problems at home or in the field. 6 levels of intensity for different situations means adjustability without clutter.
The single-dog model is the ultimate in simplicity with just one stimulation button. Its classic design has made it a favorite with dog trainers for nearly 40 years. The EXP® Model allows you to field expand up to 6 dogs (additional Collars purchased separately).
The above is directly from the website. Since he says he has 2 collars, I would guess it's the EXP model, up to 6 dogs.
