I purchased a JeoTech 2 weeks ago. So far it has performed as advertised. The max depth I've tested is 20", an empty plastic jar as a void, and it was detected. I have to find some place to dig deeper. This Texas gumbo isn't easy to dig in. I subsequently placed a mason jar lid inside the plastic jar, thus the lid was @ 20" and the Jeotech detected the void and the metal. Also filled the jar with coins and the Jeotech, Tesoro Cortez, and Minelab Explorer SE all lit up. Did some other random testing with coins and rings, but that's not why I bought it, so I didn't get too detailed. I did use the 14"x17" coil that is a part of the package they are selling these days. Have a lot more testing to do and hope to put it to use for the purpose I purchased it in the next 2 months - detecting old caches @ depths up to 30". It's a hobby so I don't get out near as much as I'd like. Hopefully I'll find someone with a two box and we can compare the devices at 18 - 30" deep. Personally not interrested in anything deeper. Though where I'm going the guy does own a bulldozer. It all depends on what you're doing and how deep your willing to dig. Everyone has a different oppinion when it comes to md's.