Washers / Collars / Shims - A washer is a thin plate with a hole generally in the middle, which is normally used to distribute the load of a threaded fastener. They can be of metallic or non-metallic usually placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevent leakage, isolate, prevent loosening or distributes pressure.

Collars attached to shafts and used as stop features or targets for devices such as tachometers. Shim is a thin and often tapered or wedged piece of materials, often used in order to support, adjust for better fit, or provide a level surface.