The backing pad attaches directly to your DA sander spindle and holds the sanding disc via Hook and Loop - it is the base plate of your sander. The interface pad goes between the backing pad and the sanding disc, adding cushioning so the disc can conform to curved or contoured surfaces. On flat surfaces, skip the interface pad and run the disc directly on the backing pad. On curves and contours, add the interface pad to maintain even disc contact.

Use the 6mm pad for fine finishing, veneer, and surfaces with only slight contours - it adds minimal flex so you keep control at P220 and above. Use the 10mm pad for curved automotive panels, fenders, bumpers, and any surface with significant curvature - the extra thickness lets the disc wrap around the curve and maintain even contact. Using the 10mm on flat surfaces introduces unwanted flex, so match the thickness to the surface shape.

Yes. The FastPlus 6" backing pad has dual thread compatibility - M8 for most European sanders including Festool ETS 150 and Mirka DEROS, and 5/16"-24 for most North American sanders including DeWalt DWAS150, Bosch, and Makita. The 44-hole pattern works with all 6" Hook and Loop discs regardless of their hole count.

Buy both if you do serious hand sanding. The FB2 longboard (15.75") is for flattening - panel leveling, guide coat work, primer leveling on large flat areas. It bridges low spots and cuts the high ones. The FB1 short block (7.8") handles everything the longboard cannot reach - door jambs, edges, spot repairs, and tight areas. Both connect to a vacuum hose and use the same 2.75" wide FastPlus rolls and strips.

Both blocks use 2.75" (70mm) wide sanding media. Compatible FastPlus products include the PURO Ceramic Velcro Multi-Hole Roll (F737, 2.75" x 13yd), the Ceramic PSA Film Roll (F737, 2.75" x 13yd), and the PuroFilm Sanding Strips FT77 in 7.8" and 16.5" lengths. The FB2 longboard works best with the 16.5" strips or rolls cut to length. The FB1 short block works with the 7.8" strips or shorter roll cuts.

Yes. The non-woven construction means they do not load up the same way sandpaper does. Rinse with water and let dry, or blow out with compressed air to restore the cutting surface. Each pad can be used multiple times before losing effectiveness. The 20-pack includes 10 Silicon Carbide pads (ultra fine, for metal and paint degloss) and 10 Aluminum Oxide pads (very fine, for wood denibbing and primer scuffing).

Replace the backing pad when the Hook and Loop surface no longer holds discs securely, when discs spin off during use, or when you notice uneven sanding patterns that were not there before. A worn backing pad is one of the most common causes of inconsistent finish quality that gets blamed on the disc. The FastPlus 44-hole replacement pad fits most professional DA sanders and restores full disc grip immediately.