This one connect to the Quattro so with just a flip of the toggle switch you have the probe turned on and this one works like a 1 inch coil as it will do everything the main coil will, except wont go as deep. You will be able to keep your headphones on and hear the same tones of the target you do with the coil. The depth is still around 3 inches or more.
The next best would be the Uniprobe that is built into the headphone, this way you get a all metal probe and a great set of headphones. This Uniprobe can be got without the headphones too and is a pocket probe that has the control box in you pocket or belt instead of in the headphones. The depth is around 4 inches with the Uniprobe, but there is no disc.
Most of the other probes have depth fron 1/2 inch to a little over a inch.
I find for the depth we dig with the Minelabs we need a good probe, why have the best detector and use a probe you almost have to touch the target to get a response, just makes recovery longer and bigger holes as we dont know where the target is.
Rick