Lifespan Tc
The maximum continuous lamp operation time. This indicator is quite approximate and the probability that the lamp will work during this period is approximately 1 in 3. This is due to the measurement technique: a control batch of lamps is used until 63.2% of them fail, the resulting time and indicated as "maximum service life". However, the Tc data compared to the B3 guaranteed life (see above) provides a good estimate of the overall lamp life and its ability to last beyond the guaranteed life.
Increased brightness
The level of increased brightness provided by the lamp. This indicator is used by some manufacturers for marketing purposes: it describes how brighter a given model is than some "standard lamps". At the same time, the standards for comparison may be different, and impressive figures (in some models reaching 140%, that is, almost 2.5 times) are not always reliable — that is, a high-brightness lamp will not necessarily be just that much brighter than the “normal” model of the same type and power.
