ViewSonic PGD-250 Active Stereographic 3D Shutter Glasses for ViewSonic DLP Link 120Hz/3D-Ready Projectors, Black TI DLP Link 3D Ready, TN Type LCD Shutter Rechargeable battery design via USB 800:1 contrast (typical), 2ms response time (typical) 40 feet effective use distance, Emitter free efficient design Compatible with any DLP Link projectors