The 63358 is a calibrated 45 W QTH source lamp. QTH lamps are known for their excellent stability in emitting high intensity visible to IR wavelength output, with minimum UV emission. Included with this lamp is a calibration certificate confirming the lamp's calibration to NIST traceable standards over a 300-2400 nm wavelength range. This lamp is designed for open air mounting instead of enclosed lamp housing operation.  Lamp replacement is typically recommended after 100 hours of use to maintain certificate value uncertainties.