First thing I tried putting it together and it wouldn't turn on, seen it had batteries in it, so I figured it should turn on. I took the batteries out to check them when I seen they were in backward only to discover if I would have read the manual first I would have seen they mentioned this as this is how they are sent to they don't turn on accidentally, shows you got to read the manual first. I do know they only put in one rubber washer as I seen this with my F-75 I had so I knew this was the case, but don't see any at all with the F-4.
I put on the 8 inch coil just to do some testing and found it to be easy to adjust the setting and the air test were great and a lot better then expected.Took it outside to a place on the side of my bar that is super trashy and it worked very well and even put a quarter on top of a rusty bottle caps I seen on top of the ground and it seen the quarter with great ID too. Next I took it out front in the street and put coins on the ground with some trash items and was very impressed at the ID and the depth it would see each target. Now I got the 4 inch coil too with it and put it on and seen the depth is OK, but no where near the 8 inch coil which was expected. I left it on and did a little actual testing in a real trashy area where I have detected with many different detectors over the years. It is considered cleaned out, but with the 4 inch coil I got a couple of deep alum cans and a few nails that were questionable, but also got a 1940 wheat a new penny plus a nickle in about a half hour with it. I did find the pinpointing to be broader that I like it to be, but by getting close to the target before hitting the pinpoint button helps a lot.
Did have a RS 3300 last year to try and it was no where as nice as this detector is.
I got this detector for my wife to use at a competition hunt on Saturday so we will see what it can do for her. I seen I could swing the 8 inch coil as fast as I could and still get a signal and good ID on a quarter with the coil 7 inches above it. I think this F-4 is going to be a real winner with what I have seen with my first impression. Just my opinion.