UL fire resistive container classifications
  class 125
n. a group of UL classifications for containers that maintain inside temperatures less than 125
degrees Fahrenheit when exposed to a fire of specific temperature and duration. The times and
fire temperatures are:
hour 1700 degrees F.
1 hour 1700 degrees F.
2 hour 1850 degrees F.
3 hour 1925 degrees F.
4 hour 2000 degrees F.

class 150
n. a group of UL classifications for containers that maintain inside temperatures less than 150
degrees Fahrenheit when exposed to a fire of specific temperature and duration. The times and
fire temperatures are:
hour 1700 degrees F.
1 hour 1700 degrees F.
2 hour 1850 degrees F.
3 hour 1925 degrees F.
4 hour 2000 degrees F.

class 350
n. a group of UL classifications for containers that maintain inside temperatures less than 350
degrees Fahrenheit when exposed to a fire of specific temperature and duration. The times and
fire temperatures are:
hour 1700 degrees F.
1 hour 1700 degrees F.
2 hour 1850 degrees F.
3 hour 1925 degrees F.
4 hour 2000 degrees F.
UL listed
adj. listed in a directory as having passed specific Underwriters Laboratories testing