I know where to buy cialis buy cialis 20mg online Nocturnal penile tumescence (NPT): This test measures a man's erectile function while he is sleeping. Normally, a man will have five or six erections while asleep. A lack of these erections may indicate there is a problem with nerve function or circulation to the penis. The test uses two methods, the snap gauge method and the strain gauge method. The snap gauge method is performed by wrapping three plastic bands of varying strength around the penis. Erectile function is then measured based on which of the three bands breaks. The strain gauge method works by placing elastic bands around the tip and base of the penis. If the penis becomes erect during the night, the bands stretch, measuring the changes in penile circumference. May not be covered by some insurance companies Stopping smoking If you need viagra now buy viagra without prescription online Article and Author Information buy Viagra 25mg here cheap viagra for sale