Ribbon bars - what period of time ?

[doughboy]

Hi altogether,

I have a question about ribbon bars. Can someone of you tell me please ,how can I date a ribbon bar from what period of time it could be ? What I could found out is that 1/2"  Wolf Brown ribbon bars were used until 1947-48 but what about 3/8" ribbon bars. Is there any reference point where I can date them , especially ww2 and Korean war era ? Any help would be greatly appreciated.Thank you in advance.