Hi Stasys, I am in the process of answering your same question for myself, but have not had enough time yet on the Tejon with the 10 X 5 Elliptical Ws coil. Been on the Tejon for several years now with the 9 X 8 and 5.75, in mild dirt, but sometimes in some really iron trashy ground too. Haven't had the 10 X5 long but have have managed to put it in some pretty iron nail infested ground that has been pounded hard by the Tejon and a few others. I did manage to find a really good button the rest left, so it did produce more from the site. That's why I decided to try it.The button was not that deep though,, maybe 5-6 ". However, on this same virgin, no modern trash, plenty iron &nails ,1811 site I have found most all my other coins and buttons with the 9X8 spoked coil, rather than the 5.75. Don't sell the 9X8 short, Of my finds before I got the EWs was a silver plated button at around 8-9" and 2 other 1/2" sized artifacts at around 10". I like the 10X5 a lot but can't say how deep it goes, but it works the iron really good. I can say that the 9X8 is a real root hog,wherever it is and probably has a wider footprint "at depth" than what it is given credit for. Many swear by the 5.75, and it is about as deep as the 9X8 but so far I seem to have made more hits with the Spoked coil. That's my meat for the pot for for now for what it's worth. Happy New Year and HH, Charlie