Shipping was fast. Added this to my Variac for better voltage indication. Was within 1V of meter reading....so good enough for my needs. Gets brighter as voltage increases. Since my variac only goes to 140v ac, I can't say if it will work at 500v. It does light up with pretty good accuracy 18V ac and above, so quite nice. I'm happy with it.
Good product & essential things for BD. cause of voltage dropped problem. Can see anytime on the display.