Active Shutter 3D Glasses for Smart VIERA 3D TVs. When the battery is charged from VIERA TVs USB (Universal Serial Bus) terminal only 2 minutes of charging gives you about 3 hours of use. With 30 minutes of charging, you get about 30 hours of use. From now on, you can spend less time charging the battery & more time watching the 3D images. Weighing only 27 g., they can be comfortably worn for long periods of time. Compliant with the FULL HD 3D Glasses Standard, these eyewear use an RF (wireless) system based on Bluetooth. RF communication enhances stability for high-quality 3D viewing. TY3D4M E glasses are compatible with Panasonic 2012 3D VIERA. (WT50, DT50, ET50, VT50, GT50, ST50, UT50, & XT50 series.) If you own 2011 VIERA model, please purchase TY-EW3D3M E.