Eye straps form light-duty mounting bases for blocks, serve as lash-down points, and can provide a fairlead on a cam cleat to hold the line at the cleat. The 201 is a low-profile cleat that fits line to 5/16".
This is one of those inexpensive but priceless pieces of hardware for a small sailboat to keep lines from "straying". It's also a great place to hook that occassional bungie cord that may be less nautical than rope, but are extremely convenient.
I used these straps to install half inch dacron double braid as lifelines on wood stanchions. This size is perfect for the half inch line and quarter twenty machine bolts were perfect for the mounting holes.