As some of you know I'm into Certina and I'm trying to put together lost information about what movements they used (they used a lot of different movements) and here is one someone might have some information about.
It says Certina 854-1 but I strongly doubt they made this movement but I just can't fine information on it. Under the balance it says MI or IW and to set the date it's a bit odd as you first need to move the hands past midnight and you hear a click, then you need to press in the crown and the date changes. In normal use it changes the date like any other movement though.
It is a mid 1970's Certina Argonaut 285.