When sourcing Antimony Trisulfide (Sb2S3), the price is primarily driven by purity levels (typically 95% to 98%+) and particle size (mesh count). For industrial applications like friction materials (brake pads), a purity of 95-97% is standard, while pyrotechnic or specialized chemical grades require 98% or higher. Ensure the supplier provides a Certificate of Analysis (COA) detailing the exact percentage of Antimony and Sulfur, as well as limits on impurities like Arsenic (As) and Lead (Pb), which can significantly affect the market value.