When sourcing grow light ballasts, you must prioritize compatibility and efficiency. Key specs include Input Voltage (120V/240V/277V) to match your facility's grid, Output Wattage (e.g., 600W, 1000W), and Total Harmonic Distortion (THD <10%) to ensure clean power delivery. Look for dimmable functions (50%, 75%, 100%, Super Lumen) which allow for energy savings during different plant growth stages. High-quality units should feature High-Frequency technology to prevent lamp flicker and maximize PAR output.