These are.great Quality clips used on 99% of all fishing pole rod racks on the market. The inside diameter is 1/2 inch and the clips will spread open wider and close back up to keep your poles secure. These are great for a DIY fishing rack ot for storage in you basement or garage or wherever, These have a inset hole to mount your clips when they are screwed in the screw head is inset and will never contact your fishing rods.These are made of about 75% Treated Rubber for durability and longevity. These are held in with one screw firmly, THESE ARE NOT THE HARD PLASTIC BILLIARD CLIPS NEEDING 2 SCREWS . MANY PEOPLE BUY OUR CLIPS AFTER BUYING THOSE . Get the best ones the first time.