Rear brake caliper parts

Looking for a part for my rear brake caliper, as it looks like mine is slightly bent. Trouble is, none of the websites with exploded diagrams on have any info on the bit I want. So, does anyone know:

A - what the part with the red ring about it is called, and

B - where I can get hold of one?

A. sliding pin 
B. dunno

That's one of the pins the caliper slides on and is protected by a rubber boot. I dont think a bolt will do it and could damage the socket the pin slides into.

You could try emailing David Silver spares. Or see if you can get another caliper on eBay.

I don't think it's supplied separately. You could have one machined up, but it would be cheaper to get a second hand caliper with one attached.

I'm not sure how easy it is to unattach it from the caliper though?

They simply unscrew - the end has an allen key fitting.

Neither of the sliding pins are separate parts either from Honda or BMW that uses the same calliper (OK mirror image)
If anyone can find some I be very interested as I had to buy used callipers to sort bikes

A second hand caliper on ebay is going for around 40 quid. Id have rather paid a tenner or so for the pin than that, but if theyre not available as spares then looks like thats the only option

and if they are you are in the same boat BUY NEW ONES if possible