The Progress Rail LED is not a very popular LED and is mostly seen on light rail and shortline railroads.  It looks like a mixture of a dotted LED and a fading LED, and at first, I thought they were RSI LEDs inside Progress frames, until I realized they are Progress's own LEDs, which I didn't know existed until a couple years ago.

Not a whole lot is known about these as Progress's website doesn't list anything publicly about this LED, but I would assume it has similar specifications to most other LEDs out there.  I presently do not have any closeup pictures of Progress Rail LEDs lit as all of the crossings I'm aware of that have this LED are on lightly used crossings that are hard to get in action, but I will try at some point to get lit closeups.  However, there is a video of them up close down below from a light rail system in Sacramento, CA.