The Porter-Cable 13905 is a 5 inch Contour Hook and Loop Replacement Pad. The Porter-Cable pad is used to sand curves and contoured surfaces with a random orbit sander. The replacement pad is designed to fit the Porter-Cable 333 Random Orbit sander. The pad accepts 5 inch and 5-hole hook and loop abrasive discs. The Porter-Cable flexible pad conforms to contours better than standard pads which prevents flattening of irregular surfaces. The replacement pad can be installed easily by using the existing mounting screws on the sander.