I would like to take the time to express my gratitude for bellicon. I have had extreme arthritis and was unable to exercise without pain. I purchased another brand with springs and it hurt me so bad I gave it away. I then called customer service for bellicon usa and was helped by someone who not only used one on a regular basis, but had the complete knowledge to help me with my order. When I received the bellicon, I was so excited that it was easy to use right away. When I started to use it I was only able to do it about 3 to 5 minutes at a time several times a day. I have Asthma and did not want to hurt myself. Within two months I was able to work up to thirty minutes at a time. After about a year and a half, I am able to rebound for 40 plus minutes at a time. I love the fact that I can work out without pain and get beautiful results in such a small window of time. I work smarter not harder!