Roof hole covers?

[Scott Forman]

I don't know the "proper" name for what I am looking for, but here
goes. On the few places on the roof that wires come up through a hole
(the musical horn speaker wires, for instance), there is a metal screw
on cover over the hole with a ridge allowing the wire to exit the
cover. When the previous owner installed the satellite, he found
something similar to use on that hole. Any idea where I might find
something like this?

Scott Forman
86 PT38
Memphis