MADE IN USA Very durable a Full 1/8 inch Thick protect your treated Posts From Water and The SUN Damage Cap presses over the out side of a 4X6 Post . Easy Can be Installed using a NAil The hole is Partially There But not completely thru until you complete the hole with either the nail or a small drill or the caps can be glued on if you Prefer. The exact Inside Dimension is 3 5/8X 3 5/8