When sourcing thermochromic jackets, the most critical factor is the activation temperature range (typically 25°C to 31°C), which determines when the color change occurs. You must verify the pigment durability, ensuring the thermochromic effect can withstand at least 30 to 50 wash cycles without significant degradation. Additionally, check the base fabric composition (e.g., polyester or nylon) for water resistance (min. 5000mm) and breathability (min. 5000g/m²/24h) to ensure the garment remains functional as outerwear.