Hi, thanks for your comment. I found out a relative of mine uses Lifepro Vibration plate. Very cheap! I know Marodynes are expensive, but if you read the page on Martin's site, it mentions the gravity of the plate and other parameters. I'm not sure I can get the same parameters with the cheaper ones, but I should research. I am concerned about my retinas. They are fine, but not like a young persons. So I wonder if vibration plates would be safe for me. Martin covers that concern for the Marodyne plate on her site. She doesn't ever talk about any other brands. That doesn't mean Marodyne is the only good brand...but I need to feel that my eyes will be safe. I've searched the internet and have not found any reports of eye damage with low intensity vibration plates.