When selecting laser pens, the output power (measured in mW) is the most critical factor. For office presentations, a Class 2 laser (<1mW) is standard and safe. For industrial alignment or outdoor pointing, Class 3R or 3B (5mW-500mW) may be required. Additionally, consider the wavelength (color): Green lasers (532nm) are significantly more visible to the human eye than Red lasers (650nm), making them ideal for large venues. Ensure the device uses high-quality optical glass lenses rather than plastic to maintain beam focus and prevent divergence over time.