Buyers must focus on precise thermal control systems, specifically microprocessor-based PID controllers that offer both Skin (Servo) and Manual modes. Ensure the heating element is a high-efficiency quartz or ceramic infrared heater for uniform heat distribution. Critical safety features should include audible and visual alarms for power failure, temperature deviation (±1°C), and sensor failure. Additionally, look for units with an integrated X-ray cassette tray and adjustable bassinet tilt (Trendelenburg position) to facilitate clinical procedures without moving the neonate.