My Plasma PIAAs say W5W on the little plastic box. Where I bought them the guy said,.................
"They are 5 Volt and the "W" is for White, it could be "A" for Amber or even "B" for blue."
He may not know what he is talking about, but since I had no answer and he was quick to give one............................................... .Maybeeeeeeeeee!!!!!!!!