circa 1950's (?) camera photo timer

Another car boot find.
This little thing measures about two inches high, and 1 1/2 across.
Internet sources came up with the 1917 patent, a picture of the illustration is included above:

https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=CH&NR=74345A&KC=A&FT=D&ND=3&date=19170216&DB=&locale=en_EP

The advert for the model "B" from 1930/31 came from this site:
http://www.camarassinfronteras.com/accesorios/photoclip_B/photoclip_B.html
and thanks for the info found there!

Not sure of the exact date, but there was a model "C" sold recently here:

http://www.ebay.co.uk/itm/Vintage-Recta-Photo-Clip-C-60-sec-Polaroid-Camera-Self-Timer-Swiss-Ma-/281857093300?nma=true&si=AC2GfTTzAgp8zSAbLY41eo6yEhg%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

These were not made after 1961 according to the site linked above, and I have found several examples like mine on various sites, this model was made to fit Leica and Rollei cameras with a Compur shutter according to the original boxes seen on ebay and other sites.

Thanks for looking.