When sourcing hydrolyzed sponges, the most critical factor is the purity level, which typically ranges from 70% to 99%. For high-end medical aesthetics, a purity of 98% or higher is recommended to minimize skin irritation from organic impurities. Additionally, verify the needle length (spicule size); standard lengths are usually between 200μm and 300μm. Ensure the product is off-white or white in color, as darker shades may indicate higher levels of residual organic matter which can cause adverse skin reactions.