Set of three pieces of magnetic screwdriver rings. To maximum ease of use, slip the ring onto the screwdriver bit and the screw is now firmly seated. These rings don't just hold, they also reduce wear on both the screw itself and the screwdriver. The rings fit 1/4 inch shank bits, which is the standard size, so they are compatible with almost any screwdriver or screwdriver. Made of steel, they will last a long time. Handy when you need to work with magnetically sensitive electronics.