OK guys ....What's the deal ? .....You just don't see the 8 inch donut on a stock 4 pin Tesoro detector ...I was checking around my test garden today and took my brothers little Silver uMax out for a spin .... It came stock with an 8 inch donut and I was hovering over a quarter that I had buried a couple years back ...It's down about 6 inches or so and I was hovering over it a good 3 inches and was getting a strong repeatable signal ..... It rained the day before and the ground was still moist , so that played a part of the equation too ...I have to say that I was pretty flipped out about hearing how good the tone sounded and how accurate the coil was on this target ...... So now I'm wondering if this would be a pretty darn good coil to use on my Vaquero ...I realize that my Vaquero needs the 4 pin and not the 5 pin on the Silver uMax ...... If you're running an 8 inch Concentric donut on your 4 pin machine , please let me know how you're liking it ....I saw only a couple of threads on this combo which seemed pretty positive ......Thanks in advance ......Also , how are the Concentric coils on the Tesoro's when using them at a saltwater beach ....NOT IN THE WATER , but dry sand / moist sand ? .....Thanks again ...