P3D Project-or-View bulb question

[Robert Cruickshank <robcruic@xxxxxxxxxxxx>]

One of the bulbs that came with my project-or-view was wearing a little
metal cap. The bulb itself had none of the usual black or blue coating on
its top, the other bulb, which had the black coating, had no metal cap. Am
I correct in assuming that the metal thingy came with the bulb, (which was
dead) and not the projector?  Is this something that is needed to keep
the projector from exploding in a ball of flame, or merely part of an old
style bulb? 

Rob Cruickshank      Toronto, Canada 
www.interlog.com/~robcruic