We have a wonderful post that we've had for at least 15 years. It's 3 sided with the three boards meeting at the top. They're on a slant and wrapped with sisal very tightly. All of my cats have used this consistently since they can lean into it and scratch away.

My husband replaced the first sisal wrap a few years ago and it's good as new. Wish I could remember where I got it. Maybe at a cat show..........?

Hard to describe, but it's kind of like a pyramid.