A friend of mine who isnt to bright wanted to get into counting, I tried to teach him but he couldnt catch on. So he goes out and gets one of these counting devices. He didnt know how it would work and i was skeptikal, I tried it in the casino well i kept count to see if when it told you to raise your bets you actually had an advantage. I have tried a certain type of device in which you plug in + and - numbers and when you want it to you hit a button and it buzzes against your leg for the count. Only thing is that when there is a high count you have to wait and wait and count the buzzes well everyone at the table waits for your dissision. I would never use these things in live casino action to make money, i think its easier to learn to count and do it in your head. I just wanted to help my buddy out and also just give it a whirl in a casino. My advice stay away from them, they truly are not worth it, plus the legal ramifications are not worth it.