Don't waste your money. Do like I do... Take a nine-volt battery and wire it to your private parts (notice I'm not being gender specific here). Then connect a simple switch to a band running around your head. When your head starts to droop, the switch closes the connection and you get a nice jolt to your scrotum or vulva as the case may be. Bam, you're right back there concentrating on the market. Works great, and it's cheap!