You will receive a bulb per post and the measured emission spectra at 4 different settings:
0.1s, 2s, 10s, 20s integration time. This will show a large number of peaks which can be used for calibrating a second spectrometer.
The emission spectra is usually available free of charge on the manufacturer's website, however in a much worst resolution..
The spectra might change slightly from bulb-to-bulb and over time as the bulb heats up, settles or degrades over it's lifetime. However, the buyer can choose to receive the measured spectra only, saving on the postage cost.