Background and aim: Many people have to sit down during daily activities. The process of sitting down especially for a long time in comparison of standing up cause many back pains. Special chairs with special backs and sits are designed for offices. industries and institutes because of back pain of sitting down for a long time and increasing the performance of employees. https://www.roneverhart.com/Ludwig-P2230B-Imperial-Tension-Lug-for-Snare-Drums-p9792/