It has no pressure gauge, so BE CAREFUL many men have injured their penises using Bathmates. It is easy to get carried away from excitement. Just a few minutes at a time, and do not pump to the point of extremely full and it can't get any fuller, if you do release a little pressure so you aren't at the max max. You will swell and gain size even if its not pumping you to 110%. I've been air pumping for over 15 years so I know what I'm talking about I've never water pumped because it can cause problems more easily and quickly. Slow wins the race, be careful, pay very close attention to any pain or discomfort (if you feel anything that feels like pain or a hurt or ouch, STOP pumping right away) and enjoy the feeling of a much fuller cock!