ViewSonic PGD-350 3D Glasses for DLP Projectors TI DLP Link 3D Ready; TN Type LCD Shutter Rechargeable battery design via USB;1200:1 contrast (typical) 2ms response time (typical); 40 feet effective use distance Compatible with any DLP Link projectors; Emitter free efficient design Supported frequency: 96~144Hz; Supports 30 hours of continuous use when fully charged