10 Magnetic Hex Extensions for Hex Head Bits. This is a new set of 10 magnetic hex extension. These are perfect for use with all hex head bits. Each hex bit is size 1/4". Each measures approximately 2 1/2" (62 mm) long. We work hard to update our descriptions and pictures of our merchandise. As part of a process of ongoing innovation by our suppliers, newer versions of the item shown may be shipped before we are able to complete an update. As a result there may be a slight variation in color and design.