Model Brand Segment Key features PA503-S Viewsonic Business & Education Light source Lamp | Brightness 4000 Ansi Lumens | Resolution SVGA | Warranty 2 years PA503X Viewsonic Business & Education Light source Lamp | Brightness 3800 Ansi Lumens | Resolution XGA | Warranty 2 years PA503W Viewsonic Business & Education Light source Lamp | Brightness […]