Hi Richard, not sure of the make I brought it off of ebay for little money, if you do get one, go easy do not fully invert straight away, start off with around 45 degrees, slowly move around a bit its not recommended to just hang for long periods, try laying on the floor arms out like a crucifix, bring your knees up and rotate both knees together to the left 20 times and then to the right, try and keep your arms and shoulders flat on the floor, this should release the small muscles close to the spine that have tightened up (popping or clunking when releasing) this should help release tension in the sacro-illiac ( I,m not a doctor but I continue this exercise everyday and especially after skiing . it has helped me) The other thing that helped me was changing my deep water start, two feet in I used reach forward to the front of the ski ( which overstretch my lower back) and pull my hips forward once the ski was on the water, my method now is to bend my knees place my hands level with them, keep my back straight, and let the boat pull me onto the water and then stand, pretty basic stuff but it takes the strain away from the sacro-illiac. Hope some of this maybe of some help, I know how frustrating it can be, for me it was particulary awkward to get position and take the load on the offside. Regards Stevie BoyÂ