Preset speed mode (high-mid-low speed), Gentle, pulsed stimulus begins to increase at a rate of high -mid-low speed. Specifically designed for patient comfort (If patient indicates perception, simply release the button. The stimulus stopped immediately, but the numbers remain frozen on the screen for about 3mins, Convenient to operate.0-40, the patient feels mild pain, means the tooth , is vital,  40-80, with above mentioned reaction , tooth is non vital. >80, no above mentioned reaction dead tooth nerve.