With round Fence Armor, our FA5x22 like all Fence Armor we recommend that you set it off the ground about an inch, inch and a half. You can use a block of wood so that you can keep them consistent if you've got a whole length of field to do so that it's accurate. When you're setting it in set the center screw in about halfway so that it is started into the into the wood or vinyl and this way it'll protrude a little bit and the back half of the Fence Armor will be able to slide underneath so that you can adjust it to the exact post diameter. This will adjust from five inches all the way up to six and three-quarters. You can squeeze it further if you like but you'd have to add some additional holes. Match up the the holes or slots on the top and then you can tighten all three but as you're squeezing them together tighten in the the center one so that its snug and now you can match up the two other screws on the top and the bottom and now all three screws will hold it in perfectly.