FM C is a class c fire door!
FM is the abbreviation of fire door, which means that no material is specified.
For example, steel fire doors are called GFM for short.
Wooden fire door is called MFM for short.
Class C is a fire-proof category, and the fire-resistant time is 0.5h
Fire doors are divided into three grades: A, B and C.
The corresponding fire resistance time is 1.5h, 1h and 0.5h respectively.