Optoma BG-ZF2100GLS, Active Shutter 3D-RF Glasses Improved contrast and black level Lightweight, stylish design with interchangeable nose pieces for customized comfort Always in sync - RF (Radio Frequency) based synchronization with 3D content Rechargeable, long-life Lithium polymer battery Designed for use with Optoma projectors with 3D VESA output and synchronization system