I have these to fill 8 holes in our patio cover. The holes were 5/8 inch wide. They fit perfectly and stood up straight away. I didn't seal them with silicone, but should the rain seep through they should pop out easily and seal with silicone. The ones at the local hardware store were about 90 cents each, so they cost about $8 with taxes to get 8. So I got 50 for $7.