These looked beautiful but did not work for me. It says in the description it fits on the wood post. We have white sleeves over our wood posts. Thus these did not fit.They were easy enough to put on my 4X4 vinyl fence posts and look fine. The problem is they only stay lit for about an hour or two after sunset, with the rare exception of maybe a little longer for one or two of 6 of them. I assumed it was because of the limited direct sunlight on that side of my house, but they worked much better initially. Some no longer even come on after about 6 months. I pulled out the battery from one of them and it is a non-brand plain label that says NNi-MH AA 400mZh 1.2V. I am ordering some new batteries and I'll see if that makes a difference. They were originally about $40 for the box of 4 when I bought them about half a year ago. They have gone down significantly since. They are relatively cheaply made and I don't expect they will survive a big storm, although they've somehow managed to hang on during a recent Hawaii storm. The lighting is more decorative than functional. If you buy them for that purpose and recognize they are not likely to last a terribly long time, you will be fine.These are almost half an inch off 4" but it will fit your standard wooden post since they are 3 1/2" Our fence had two different installations, so it won't fit the newer wooden posts but we had no problem with our older posts. It fits perfectly and we could almost just leave it like that, except it get very windy over here so we were able to use the screws it came with to drill it into the wood. Unlike other brands, the top is easy to remove to change the batteries, I'm not sure if I have to buy special batteries for it or just regular AALove these! So pretty!Haven't had them but 2 daysNice accent for our deck this was easy set up for me I literally was able just to lift the cap off of our post and stick these on and right away that first night they lit up very nice to have the solar powered lights nice little accent.