PAR = sealed beam width across is measured in 8ths
A standard PAR size is PAR30 I'd suggest googling for PAR30 12volts
screw terminals.

A good source of info is the General Electric Lamp catalog:
http://tinyurl.com/24ma95x

On 6/18/2010 8:19 PM, Tom Horne wrote:
I need help identifying the proper nomenclature for sealed beam bulbs
of various sizes and wattages. I have several hand lights that I
would like to convert from the old hard to find six volt screw post
batteries to the newer twelve volt type. I just don't know the proper
nomenclature for a twelve volt sealed beam lamp that is three and a
half inches across and is connected by screw terminals on the back of
the lamp.
--
Tom Horne