Greetings to all. I just purchased a few used machines a few days ago from a detectorist in pennsylvannia. A whites 5900 di pro sl with the bill lahr tone modification, a tesoro toltec 100 metered machine and a tesoro royal sabre. The machine I'm excited about is the 5900 di pro with the tone modification. It has a toggle switch on the outside of th case to switch from mono tone to multi tone.I have never seen another 5900 with the tone kit although I'm sure there are, but very few. This machine is mint condition and came with about 8 coils from 4 inch all the way to 12 inch. The large metered machine is absolutely beautiful and so far performs in my test garden flawlessly. I p lan on putting to the test on some old sites in a few days. I've been detecting about 35 years and really did'nt need any more machines but I could not pass up the opportunity to add this rare 5900 to my collection. I paid serious money for this machine but based on condtion and rareity , I had to have it. I'll play wih it for a while and probably end up selling it a some point, but right now I'm going to give it a work out...........Steve