Does anyone know how to identify minature wedge type bulbs? I am looking for two 12 Volt 21 Watt bulbs but they can't have a large diameter due to the hole they must fit into. I know they exist because I have one in the bike but it's in an aftermarket turn signal and I don't know any details about it. All the bulb says on it is "12V21W" no other numbers or identifying info. I've searched the web with no results. I thought knowing how to identify the specific type could help me narrow the search.