I think you are talking about the Platinum Pro, instead of the 8 inch coil, it comes with a 11 inch DD coil, I own a Platinum, and bought a 11 inch coil for it, but the original 8 inch, in my opinion, works better with this unit, the 11 inch is supposed to give more depth, but the 8 inch beats this coil, specially in the all-metal mode, another thing, the detector with the 11 inch coil raised the price one hundred dollars, but the 11 inch coil costs $169.00.
This is not a bad deal, but there are only two distributors, Cabela's, and Detector Electronics (metaldetector.com), but don't go to Cabela's, this detector with the 8 inch coil goes for over $500.00, whereas metaldetector.com sells it for $300.00, and they give a bunch of extra stuff with it, the people who own it and their reps are very knowledgeable, and very polite, excellent Customer Service.
I've found a lot of coins , a man's gold ring, a silver and turquoise bracelet, a cob-like Spanish coin, in only a few hunts, this detector is worth more than what you pay for it,
Good Luck