Looks Honeywell Linear to me. They used very similar type of mount on the Compaq Enhanced keyboard series. http://www.ebay.com/itm/Unisys-F4208-00 ... 2c67e48190
Scroll down there is a pic with the cap off. Looks similar.
Where did you find that picture? Surely there must be a large version and a picture of the rest of the keyboard in which is found? Unless of course this is a contest in disguise and you already know!