Start with the complete specification.
A useful specification sheet describes the equipment and the conditions behind its measurements. A single large number rarely tells the whole story.
Wavelengths and controls
Look for the wavelengths in nanometres (nm), whether channels can be selected independently, and which controls the panel provides. The concept figures on this site are examples, not confirmed device outputs.
Measurement conditions
If a specification includes irradiance, check the stated distance, measurement method and area. Figures measured under different conditions may not be directly comparable. LED count alone does not describe the light delivered at your position.
Practical details
Confirm dimensions, weight, mounting hardware, power requirements, ventilation clearance, included accessories and the manufacturer’s instructions. Ask for clarification on any missing information before buying.