That’s a good question. Here’s our official answer from the FAQ:
You don’t need two bands, but having bands on each hand increases the efficacy of alerting you whenever you touch your face. Putting one band on your dominant hand will alert when that one hand touches your face, which is more effective than no alerting.
In my experience using our similar product for nail biting, one bracelet is more than half as effective than two bracelets. There are two reasons for this. The first is that putting a bracelet on my dominant hand catches more than half of face touches. But more importantly, the device is designed around the idea of awareness. In my personal experience, awareness of nail biting with my right hand generalizes (substantially, though not completely) to my left hand.
Cool idea! Do you need one for each hand to make it effective?
That’s a good question. Here’s our official answer from the FAQ:
In my experience using our similar product for nail biting, one bracelet is more than half as effective than two bracelets. There are two reasons for this. The first is that putting a bracelet on my dominant hand catches more than half of face touches. But more importantly, the device is designed around the idea of awareness. In my personal experience, awareness of nail biting with my right hand generalizes (substantially, though not completely) to my left hand.