Can somone tell me what this is ?

[Aaron Scheuerer]

I was up on someone's roof today and came across this lovely item. I'm a newb and haven't seen anything like it it yet

[Mark Reinmiller]

Not that common around here, but I think it is a rain sensor for a lawn sprinkler system (so the system does not operate when it is raining).

[Jerry Peck]

Lawn irrigation system rain sensor switch.

Bypasses the sprinkler system timer so the system does not run when it is or has recently rained.

That's the intent ... whether or not it is actually working or even connected into the system is not known.

[Aaron Scheuerer]

awesome thank you so much guys Ive never seen that in my life! Learning every day

[ROBERT YOUNG]

Here is a link to a Rain Sensor. http://www.rainbird.ca/landscape/products/controllers/RSD.htm