On 10/03/2013 09:12, Bob Eager wrote:
I tried Farnell but I'll look at RS. They do at least exist, then.

We used to key our cable so you had to put them the right way around.
However as I only ever ordered the ready made cable I've no idea where
you get the bit of plastic. Thinking about it I've never see one loose -
so I can only tell you the head was square, and had a mark in the top as
if it had been broken from a bit of sprue.

Andy