When evaluating Bamboo Spandex (often called Bamboo Jersey), the most critical factor is the GSM (Grams per Square Meter), which determines thickness; 180-220 GSM is standard for t-shirts, while 250+ GSM is preferred for leggings. The composition typically ranges from 92% Bamboo / 8% Spandex to 95% Bamboo / 5% Spandex. Ensure the supplier uses OEKO-TEX Standard 100 certified yarns to guarantee the absence of harmful chemicals, and verify the pilling resistance grade (aim for Grade 3-4 or higher) to ensure long-term garment durability.