Search in Tower Hobbies under Proctor Pulley.
Also referred to as "Block", see http://www.westbourne-model.co.uk/ae...t-Fittings.asp

I am a bit more pragmatic, and I use a 2-56 eyebolt to guide my water rudder cables. Sure it's not as scale, but it is easy to set up, reliable, and you can buy a pocketful of 2-56 eyebolts for what a proctor pulley costs. I use the braided fishing line for my cables, so the eyebolts are about like the guides on a fishing rod to the cable. I Never abraded a cable yet.