How the part fits? The 8-1/4” wire ties are designed to go around line posts and over top rail.
Where is it installed? The 8-1/4” wire tie is installed every 24” on the top rail, and for your line post you will have the height of your fence minus 1. For example: for a 4’ fence you will have 3 wire ties. The 3 ties will be evenly spaced out, the first one 6” from the bottom and the last one 6” from the top.
How many do you need? You will need one wire tie every 24” for the top rail, and height of your fence minus 1 for each line post.