The info below may be incorrect
The model of your bros should be written on a white sticker near or on
the colour label (Look at the diagram below).

The diagram below is for a Honda NT650 Hawk GT
My Bros NT400J does not have a "vehicle identification number"

Product one refers to the 650cc version and Product two refers to the 400cc version.

If your frame number lies between the numbers devided by the "~", then thats your bike

Model Product Frame Number
BROS NT400J 2 NC25 1000001~1008753
BROS NT650J 1 RC31 1000001~1002543
BROS NT400K 2 NC25 1050001~1053898
BROS NT650K 1 RC31 1050001~1050698
BROS NT400K 2 2 NC25 1053899~1053958
BROS NT650K 2 1 RC31 1050699~1050898
BROS NT400L 2 NC25 1100001~1101011
BROS NT650L 1 RC31 1100001~1100313
BROS NT400L 2 2 NC25 1101012~1101231
BROS NT650L 2 1 RC31 1100313~1100663