Design Principle ：When the person is flat on the lumbar massager, pushing the waist up and down with the gravity of the human body plus the inflation air pressure will help us to perform dynamic stretching exercises. You don't need to move, the device will help you move and stretch your waist,lumbar massager Stretching up and down amplitude is 4CM-10CM.if you simply want to buy massager, it is not recommended to buy Auxiliary Infrared Heating：The heating function provides a soothing and invigorating heat that delivers a warm and gentle massage. lumbar massager will leave your muscles relaxed while getting rid of all aches and fatigue. To get the best stretching effect, JKAH-2 will provide the thermal theray , Three leves :LOW/MIDDLE/HIGH ,which can adjust from 45 to 65℃. Buy one set with Three functions, main function dynamic back stretching device, auxiliary function: massage + auxiliary heat，If your main purpose is to buy a massager or hot moxibustion function, it is not recommended to buy our products, our products are mainly lumbar massager.