I have a big, black cat and big, black cat tower. The tower was purchased secondhand and two of the upper platforms were wobbly. The cat tower supports I designed and printed have made those platforms decidedly unwobbly. The diameter of the post hole is 2.79 inches (70.86 mm) , which fit very snug and secure on my particular tower. There is a cut version which eliminated overhang for one of my posts (see pictures). I have included .step files so you can make your own adjustments/remixes. If you make it, please post a picture of your cat. :)