Mercury PAR 38 100 watt lamp. – This bulb is a high efficiency source of actinic radiation, and is used for a number of special applications which take advantage of their strong ultra-violet output. Commonly used for fault and crack detection in alloys. H44GS-100M Mercury Vapour 100W PAR38. BULB/LAMPE/BOMBILLA. E26-E27mm screw cap.