You know what, Golden, I LOVE, that 5" coil for super trasy areas, it really does seem to separate the targets very well, but deep down, in my soul, or should I say, my (empty)pocket book, somewhere, I secretely want a 14" coil to mess around with. I'm just dying to see if it REALLY, finds deeper stuff, and my thinking is, it could cover more ground per minute because it's a bigger coil. The 18"???. That could be pretty scary too, but, I'm worried that might be "over kill", but again, I don't really know. My main concern here is, is it sensitive enough to find the smaller targets, etc., being such a large coil. Get my drift? What got me going on this stuff, is not only reading the posts at Kellyco, but I actually ran into a guy down at Ocean Beach, here in San Diego, on afternoon, who had an Excallibur with a HUGE, (probably 18") coil attached to it. I didn't give it too much thought at the time, but later on, I got to thinking, boy what a setup. Not only could he go into the water, but he could go really deep and cover a tremendous ammount of ground in less time. Of course, you could move that idea right over to the Quatro, and not get the housing wet, but still go deep and cover much ground.