2-Pack Norton Backup Pad For PC 7800 (Replaces SPBP) Norton back-up pad is for use with the Porter-Cable model #7800 drywall sander and Norton hook & loop sanding discs. Using the hook & loop system is more economical and effective than using the stock pads with glued abrasive. Use several sheets of sanding discs without having to replace the foam back-up pad each time. Easy attach sheets with Hook & Loop Foam pad attaches to sander with the stock nut Far more economical than stock discs