Do these mount to the factory mirror brackets?

Yes. These bolt directly to your existing towing mirror without additional drilling or adapter plates.

Will these lights stay secure at highway speeds?

They're designed for direct mounting to rigid mirror hardware. Once fastened, they won't shift or rattle—same as OEM markers.

What comes with the kit?

You get the left and right light assemblies. Mounting hardware and wiring connectors are not included—refer to your truck's service manual for torque specs and electrical integration.