At some point the 851 became part of Federal Signal, who made the base a little shorter (they also offered a smaller lensed version). Soo line used a number of these in Red and amber. These are also commonly used RC light on modern engines.
4 unpainted clear parts per sprue with 1.3mm mounting pins.
Instructions for lighting are provided on the packaging. We will have a blog post on how to use our strobes
and beacons in the near future.