This is the replacement mercury bulb for the Mercury Light Source. That Light Source is used for the light source for the Photoelectric Effect but can also be used as a standalone mercury light source for spectrum experiments, such as used with the Educational Spectrophotometer.
Both the Mercury Light Source and the Photoelectric Effect ship with this bulb. This is strictly a replacement part for the light source.
CAUTION: UV LIGHT; WHEN USING THIS PRODUCT, DO NOT LOOK INTO THE LAMP. UV RAYS MAY BE DAMAGING. WEAR PROPER EYE AND SKIN PROTECTION.