We used a stud finder. Even after attaching to a stud, the post gets wobbly after use. Not sure how long these will last with my energetic 9lb cat.
I have had this for a couple months just never got around to putting it up. I just put it up and my cats love it! I live in a loft so its important to have ways up and down the walls or I am sure my cats would make their own.
These are super sturdy and easy to install. Great for kitten climbing!