When sourcing period panties, the most critical technical aspect is the multi-layer leak-proof technology. A high-quality product typically features a four-layer structure: a moisture-wicking top layer, an absorbent core (often microfiber or bamboo), a leak-resistant TPU breathable layer, and a comfortable outer fabric like organic cotton or modal. You should verify the absorbency level (e.g., light, medium, heavy, or overnight), which is usually measured in milliliters (ml), ranging from 15ml to 50ml per pair.