When sourcing LED halogen replacement lights, you must prioritize Luminous Efficacy (lm/W) to ensure energy savings without sacrificing brightness. Key specs include Color Rendering Index (CRI >80 for general use, >90 for retail), Beam Angle (typically 15° to 60° for spotlights), and Heat Sink Material (aluminum is preferred over plastic) for thermal management. Additionally, verify the Driver Compatibility, especially if the buyer intends to use existing electronic transformers, to prevent flickering or premature failure.