The Xcelite 99-21 is a 1/16" x 4" hexdriver blade. Series 99® blades, shanks, and handles are available separately or together in sets. Because they're totally interchangeable, you can mix-and-match whatever components are needed for the job. When your requirements change, and a different set of tools is necessary, your set of blades, shanks and handles can be modified or enlarged at minimal cost. Blades and shanks have been specially constructed to tension-lock into handles and work, together, as firmly as a one-piece tool. Ideal for service technicians who need an extremely portable set of tools.