Review on Z Hex Flush Internal Threads with Threading by Robert Berio

I used these inserts on a set of pens for small projects. I put them in premium pine plywood (if you have them). I used a regular Allen key and it was very difficult to get them to go right in. Once they start there aren't really any fixes. I also had to take a hex wrench and hit it with a hammer to seat it in the threaded insert before driving it into the wood. Otherwise, the wrench would slip out almost immediately. It looks like a 'feature' of the design, so they're really reaching for the tool. It was annoying but it worked. The thread is strong enough. I tried inserting a 1/4 20 screw like a real monkey and managed to strip the threads off. Once they take over a few threads I'm pretty sure they are as strong as you need them to be. Bottom line - they work and they are good value for money.