After 2 years of back pain (despite compensation Sports) I have introduced these chairs for all and am thrilled:
After 6-8 months (lower back / lumbar) were with my wife and my back pain disappeared.
The active sitting by tilting seat and only sporadic leaning on the small backrest support the back muscles in good measure.
When's the employer does not pay: such furniture for individual health maintenance is strongly recommended mE - we see it several times a day the spinal damage from non-welfare of office workers ...