From Lone Wolfs web site

"Fits 4” – 24 ” tree diameters (3 foot strap extensions available)"

I have a set that I bought at the beginning of last year. I really love those things. Around here, treestands and steps disappear if left in the woods. To that end I now use the climbing sticks to get up 16' where I leave a couple of steps screwed in. I have not lost a single step or lock on chain yet.

The only thing I don't like about them is the velcro strap they use to secure them together when carrying. You can hear that stuff for seem like miles on a quiet morning.