The PR21W automotive bulb is a single filament bulb with a BAW15s base. It has a nominal power of 21 watts and is designed to operate with both 12V and 24V electrical systems. This bulb is specified to emit a red light output, which can be useful for certain automotive applications.
PR21W Light Bulb
BULB CROSS REFERENCE
The PR21W light bulb family is interchangeable with the following bulbs
In terms of interchangeability, the PR21W bulb can be replaced by other bulbs with the same base and power specifications. For example, the P21W bulb is a similar single filament bulb with the same BAW15s base, but has a slightly higher nominal power of 21.5 watts. However, it is important to note that different bulb types may have different light output characteristics, so it is best to consult with a professional or refer to the vehicle's owner manual when replacing automotive bulbs.