After having a couple of roof windows installed I’ve found some of these clips/rivets lying around having been removed from the roof and discarded by the contractors. They appear to be made from copper.
I can see from the undisturbed areas of the roof that these devices help to prevent wind uplift; the circular disc part hooks under the edges of adjacent slates and the “spike” passes through a hole on the lower edge of the overlap slate and is then bent over. But what are they called? I cannot find any reference to them on the Internet.
