describe: This inflatable ball is used to compress air and has a wide range of uses. There are metal sheets. The valve, which can control the air pressure and release the air by turning the knob. it is made Exquisite workmanship, good air tightness, theoretically can be used for dozens of thousands of times. feature: 1. Quick response, stable operation and long wearing time. 2. It can be used for medical equipment accessories, such as blood pressure monitor, air neck traction, inflatable bag, etc. 3. With manual and adjustable functions, it is easy to use. 4. Suitable for sphygmomanometer, air neck traction and air pillow. Specification: 100% brand new and high quality Applicable to: sphygmomanometer, cervical traction device, inflatable pillow, massage pad, Size: 11 cm / 4.33 inches Material: metal + plastic Package list: 2*Sphygmomanometer ball