When selecting a GAOKEView projector, prioritize ANSI Lumens over marketing 'Lumens' to ensure brightness accuracy; for classroom or office use, a minimum of 3500-4000 ANSI Lumens is recommended. Verify the Native Resolution (ensure it is at least 1080P or 4K for professional presentations) and the Contrast Ratio (aim for 20,000:1 or higher) to ensure sharp text and vivid images. Additionally, check the Light Source Life, prioritizing Laser or LED sources that offer 20,000 to 30,000 hours of maintenance-free operation.