The Round Pad Eye is used by many manufacturers to run rudder lines or deck lines along the side of a boat. They are made of high quality nylon to ensure they can take the abuse and strain that today's kayakers can dish out. Sold individually.
I love using these...especially for rudder lines. They really keep deck lines smooth and give installs a much more professional look. Very easy to install, even with well nuts as long as you use longer screws.
Works great for anchor trolley, has a low profile and cost less than a pulley.