First of all, don't buy this if you can't take hanging upside down, or partially upside down. This is an inversion table, and called such because it "inverts" your body, and so you're put into an upside-down position. Also know that this device can increase the pressure in your eyes, so if you have eye trouble, check with your doctor first before jumping right in.
That being said, this is a great device that "stretches" the spine. I use the word stretch, but the effect on your spine is a little more than that. When you use this machine, and your body is inverted, this imparts a traction force on your spine, which distracts your vertebrae. So, traction is the force that the inversion table puts on your spine, distraction is the effect.
Now when your spine is distracted, the vertebrae that arw stacked on one another (with a disc in between them), move farther apart from each other- which takes pressure off the discs that lie between them- and this is a very good thing for your discs. This is because the discs are being compressed all day long as we move around in an upright position. Know that the discs have a high water content, and as you sleep in a horizontal position in bed, they actually swell a bit as they pick up water overnight (because they're not being compressed). Then, when you get up in the morning and move around all day with your spine in a vertical position, this water is expressed to a certain degree throughout the day. This is why you are a little taller in the morning than at the end of the day!
As you can see, this device is very good for your discs- especially ones that are herniated. Other good things this device can do for you is take pressure off pinched or compressed spinal nerves in your back. Since the inversion table distracts the vertebrae a little, this moves them farther apart- which gives the nerves that come out between them "room to breathe".
Lastly, because you're hanging upside down, your back muscles don't need to work- and so they get a chance to relax and get a break! And relaxed muscles make for a happy back...
Consider using an inversion table if the idea appeals to you and you don't mind hanging upside down (or partially upside down), and the
Body Champ IT8070 Inversion Therapy Table would be a good pick. About the only bad thing I can say about it is that it does nothing to strengthen your back- and for that, I suggest checking out books like
Treat Your Own Spinal Stenosis. Good luck!