This is a 1/4 Inch (6.35mm) screwdriver bit handle. It allows you to comfortably use any standard diameter screwdriver bits / drill bits / hex attachments like a regular hand tool screwdriver. 👉Q. Why did I make this? ➖A. All my handles have an additional shaft on them. This is fine when using shorter bits of 1 inch or less, but is impractical for longer bits like the one in my photos. A shorter shaft improves torque control and reduces angular play. Put simply: This handle just feels better.