This instrument is specifically designed to evaluate blood vessels for venipuncture.It uses a healthy infrared light source to visually display the superficial blood vessels under the skin. Infrared vein display instrument Is a special display of wavelengths different interleaving;it irradiates human skin , so that the superficial veins under the with shadows appears in front of the viewer with eyes, this effectively improve the efficiency of venipuncture. Try not to use under strong fluorescent lamps, the dark space effect be more obvious, and it does not affect the use of the room during the day. Blood vessels in the superficial skin were visible, but not in the deep skin.In addition, the effect is not obvious in obese or thick people. The USB port can be used when plugged into a computer, a power bank, or a power socket. When in use: the switch Moving the close to the skin can help you find blood vessels and veins Carefully observe and operate after seeing the blood vessels Note: Do not look at the infrared light source with your eyes, if you feel harsh, you can wear sunglasses. Battery: Polymer Lithium Battery 800mah(About 8 Hours) Size: Total Length 154mm/6.06inch x Head 46mm/1.81inch x 28mm/1.1inch(Handle Width 24mm/0.94inch x Thickness 19mm/0.74inch) Light Source Form: Led Mixed Wavelength Switching Mode: Middle Button (One On And One Off) Operating Voltage: 5V(Plugged In) Or Product Weight :150g Color: Black Material: ABS Package Contents: 1 * Infrared Vein Viewer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.