Nantucket Post Caps are sized according to the actual physical measurement of your post. All post caps are made 1/8" larger on the opening then the actual post size you specify. For example, if your 4x4 standard post truly measures 3-1/2" x 3-1/2", then you would choose that size and your cap would come with an inside measurement of 3-5/8" x 3-5/8". Colors and sizes vary by selection.
All Nantucket Post Cap Products are Proudly Made in the U.S.A.
The Copper Slip Over Post Caps from Nantucket are real copper and will patina over time.