1. Lock the application first
Record the bulb size, target market, vehicle or application context and any installation constraints before comparing models. H4, H7, H11, 9005 and 9006 are different fitment routes, not interchangeable labels.
2. Ask for optical evidence
Compare low beam, high beam, cutoff behavior and model-specific test imagery where available. A useful supplier answer should connect the claim to the exact model being quoted.
3. Review heat and electronics
Cooling architecture, driver design and CANBUS requirements can affect suitability. Treat CANBUS compatibility as vehicle-specific and verify it for the intended application.
4. Turn the shortlist into an RFQ
Include estimated quantity, target market, packaging or private-label needs and the evidence you still need verified. This makes quotations easier to compare on the same basis.