Most ignition key switches have a 'D' shaped neck so they don't rotate when you turn the key. However, most people don't have the necessary D-shaped drill bit :-), so Lowbrow Customs made these convenient tabs. Made in Ohio, USA. 
Stainless steel bolt-on style for the primary cover of 1991-2003 Sportster and ignition switch with a 13/16" (20.6mm) neck