The Harley-Davidson turn signal brackets are machined in the mass. They are made of 2 mm thick steel and are coated with a matte black epoxy paint. The diameter of the hole is 8.5 millimeters and will allow you to put all styles of turn signals with stem. The kit includes a pair of fasteners for the left and right rear turn signals, they will match the shape of your original turn signals. They will fit your Harley-Davidson Nightster perfectly. (Turn signals are not sold with the kit).