PSA Stands for Pressure Delicate Adhesive. These are typically self-adhesive sanding discs that promptly and easily attach to the sanding device. Obtainable in possibly cloth backing or paper backing with fabric getting used for heavy obligation grinding and paper being a far more cost-effective and light-weight option for lighter sanding/finishing. https://www.quora.com/profile/Trevor-Flatcher-2/Application-and-Development-of-Silicon-Carbide-in-Bulletproof-Ceramics-Silicon-Carbide-in-Bulletproof-Ceramics-Applica