The Snap-Gauge device has been used by physicians for several years to help distinguish between physical and pyschological impotence.
Most healthy men experience about three to five erections in their sleep each night.
It's color-coded plastic elements will break if you've had a normal erection. If all the plastic strips don't break, your impotence is probably due to a physical cause. You can discuss these results with your physician or urologist, and take steps to finding a solution that's right for you.