Finding oil leaks, inspecting belt wear, or reading part numbers on the back of an engine block is impossible without a direct line of sight. An inspection mirror allows you to look around corners and behind tight clearances. It features a small glass or polished metal mirror attached to a ball joint at the end of an extendable metal rod.
The ball joint rotates 360 degrees, letting you adjust the mirror to the exact angle needed. Many modern versions include built-in LED lights to illuminate dark areas behind the engine or under the chassis. Wipe the mirror glass clean before use to get a clear image. Avoid using glass mirrors in tight spaces where they might strike metal and shatter, opting for polished stainless steel mirrors instead.