Judge by 10 mm thickness and 4.4 V peak, not by a Drop-shaped lifestyle photo.

Step 1. Read 20 × 82 × 10 mm. If a listing only says “air” or “slim,” it is not answering WINDBAR D91 vs Suorin Air slim.

Step 2. Read 4.4 V peak. Do not copy a Suorin voltage onto D91.

Step 3. Confirm a complete lineup or single-edition still. Full devices, not half-cropped thumbs.

Step 4. Color does not change millimetres.

Step 5. Use the WINDBAR ohm’s law calculator for 4.4 V math. Packaging wins.