Thank you for viewing. When I started my hardware store 45 years ago, they were still on the shelves. Electric screwdrivers were already available, but there were still many craftsmen using these. Customers would come in saying things like "Give me a knuckle," and they were commonly called "knuckles." So, as in the image, they have a "knuckle" mark, which is their trademark. This product allows you to tighten and loosen plus and minus screws more easily than with a hand-powered screwdriver. It's not a practical item these days, but it might be interesting as a collectible. It does come with one plus and one minus bit, so you can use it, and it works perfectly. The box and instructions are dirty, but I think it's rare to find one complete like this.