1.Theory of SHR is a new technology of permanent hair removal which is having a sweeping success. The working theory is heating the dermis to a target temperature gradually, at that target temperature; it damages the hair follicles and prevents re-growth effectively, meanwhile avoiding injury to the surrounding tissue. A high repetition rate of single pulses are delivered deep into the dermis, achieving high average power and effective heat build-up, without the risk of injury and no pain virtually.