Plastic Sander Pad with Velcro Size :4", 4.5", 5", 6" 7" Shape :Abrasive block backing: ... Velcro or PSA. good quality Plastic Sander Pad with Velcro Size :4", 4.5", 5", 6" 7"Shape :Abrasive block Features ... , M16. 3) backing: Velcro or PSA. We also can produce different size and thread as customer request. Plastic sander pad with velcro ...