Thank you for that..As I said my grandfather had it since the 50s and since 1980 when he passed I have never touched the watch till now..I was wondering what the arrow was for. Thanks again for your reply.Nice example. It has a version of the EPSA compressor case. The tab on the case back indicates that.
As it is an automatic, my best guess is that it has a 1035 movement.
They are very robust watches. Well worth getting it serviced my a competent watchmaker. Also, be certain to point out that the case back is not a screw off. It is snapped back into place using the little arrow lined up with the crown.