I've had some difficulty using these toggle clamps. Before you buy a mug, be sure to familiarize yourself with the different styles, how to properly set up mugs, and how to use them in your projects. This would be helpful in choosing the best style for your application. I also watched some videos on some very interesting uses. I thought I knew how they were supposed to work but unfortunately we don't read the instructions. I intend to keep them and build suitable devices to use them. Manufacturing may include clamping screws.