The 1N5375B is a Zener Diode with cathode band polarity.
**Zener Diodes 5W Surmetic, 1N5364 to 1N5388 Series, ON Semiconductor** A complete series of 5 Watt Zener diodes with tight limits and improved operating characteristics.
The BZT03 series Zener Diode with glass passivated junction and hermetically sealed package. It is used in medium power voltage regulators and medium power transient suppression circuits.