Its a mid range Whites from 1997 on. I think it runs at 6.592 kHz. Coil was concentric at just under eight inches.
If you think it works well you should try the Quantum XT (QXT) or QXT Pro. Both are far better with the XLT type 9.5" coil and the ability to turn noise reduction off. Turning it off gives much improved depth.
They did offer upgrades so your mate could have his taken up to the next level. Well worth it.
The only drawback was that there were some areas/mineralisations where they didn't work to well and you couldn't do much about it.