Compare the actual size
Penny, 2-inch, 2½-inch and 4-inch listings require different fitment checks. Compare housing dimensions, mounting opening, depth and connector clearance. A round face or matching nominal diameter alone does not confirm a replacement fits.
Match function & output
Marker/clearance lamps, turn signals and back-up lights perform different jobs. Check the exact lamp’s function and emitted colour. Dual-function and dual-colour describe different features, so review the model’s operating modes and wiring.
Check lamps versus kits
A lamp-only listing and a kit may supply different components. Confirm quantity, grommet, plug and mounting hardware before ordering. Check voltage and connections for the selected model; heated and auxiliary options need their own installation checks.