Only HQI bulbs need a piece of glass because they produce UV rays. A mogul based bulb does not produce any UV rays so it does not need any glass. Hope this helps.
Mogul base bulbs do produce UV but the glass envelope of the bulb is the shield. A mogul bulb is nothing but a HQI bulb with a built on UV shield.
ALL HQI bulbs MUST use a separate UV shield.
02-16-2008, 02:28 AM
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