Cool vintage retractable pencil

My late Grandfather (1905-1987) spent some time as a plastics salesman before the 2nd world war and sold casein products for Erinoid in the UK.

I have quite a few of the products he sold as my father passed away last year and they have been handed down to me because I love this stuff. I thought I would post some pics of this retractable pencil because it is a pretty awesome example of a multi function product which is what smartphones essentially are.

This one has a built in calender. The back cap is threaded and hold in the extra leads, but also allows you to rotate the days to match the calender number. It also writes pretty well.