I think the channel model specifies the standard of cross section, and -39 refers to the length of the channel. Thank you for your answer.
39 is certainly not the meaning of specifications and length, may be weight
10# channel steel, size is 100 wide, leg height 48, thickness 5.339 may be the number! This should be based on specific drawings
100*48*5.3 is the type of channel steel, there are a variety of models can be found, 39 refers to the length of channel 39mm.
That is to say, 10# channel steel, size is 100 wide, leg height 48, thickness 5
