I bought the treasure hunter vibro-probe around a year ago. It works OK - but it is a bit too long, the tip is a bit too fat, and it does not have much depth capabilities. It also only vibrates and has no tone setting. It is totally waterproof which makes it nice. I use it when I dig a plug and want to find the target
more quickly than having to half up the plug and wave pieces of the plug around in front of my coil until I find the right chunk. The draw back with the Vibro-probe is it has an auto on and off feature. That may not sound like a drawback, but for me it is. If I leave the battery in and carry it around in my detector bag, it will go on and off all the time when I don't want it to - which runs down the battery and it becomes somewhat of an annoyance. I would go for a pin-pointer that has both a vibrating and sound function, and one that has a simple on and off switch. If you are talking about a simple coin probe - like a long screw driver looking thing - I don't use one. A friend of mine swears by them. He says they can help prevent damaging a valuable coin by helping to not hit something valuable with a digging trowel. He spends about 5 minutes on everything he tries to dig by probing around trying to locate the exact location of a coin or valuable, when I move on from coin to coin while he is still probing around. If you find a place where you know there may be lots of very old and valuable coins in the ground, a probe would be the right thing to use in order to help prevent damage........I guess. However, since I have never found anything really old - I have not given it much thought.