The 'D' shaped hole is a perfect fit for the Lowbrow Customs Weatherproof Starter Ignition Switch (the last ignition switch you should ever need to buy for your bike

Rod Length: 318 MM / 12-1/2"

FXRS CONV 1EML LOW RIDER CONVERTIBLE (1991)

This lower bushing nut wrench is made out of 3/16 inch thick stainless steel and has a tumbled finish

qty 2 000089 Threaded Bungs 5/16”-18 x 1/2”

#2029-5 Front Axle Nut Grooved Spacer Kit 2000-2006 Harley-Davidson FLSTF/FLSTF - Chrome Plated Length_.648" The 'D' shaped hole isAxle nut, washers and spacers, OEM# 43617 00 and 43683 00, add a custom look to all 2000 2006 FLSTF and FLSTFI. Made in Ohio, USA.