Mirka 23-321-320 5 in. 5-Hole P320 PSA Sanding Discs are adhesive-backed sanding discs sold in a 100-pack for fine finish sanding with compatible 5-inch sanders. This is a PSA sanding disc set designed for finish sanding on a matching 5-hole pad. Model Number: 23-321-320. If you need a finer grit for surface prep, finish leveling, or the last passes before coating, this pack gives you the quantity and consistency to keep moving without constantly swapping brands or grit lines.

The big selling point here is the P320 grit. That is firmly in fine-sanding territory, which makes it useful when aggressive stock removal is already done and the goal shifts to refining the surface. On the job, that means fewer deep scratch marks to chase later and a better starting point for paint, clear, or other finish work. For wood, metal, and other surfaces that need a cleaner final prep step, that matters more than raw cutting speed.

Mirka builds these discs with aluminum oxide abrasive, and that is a practical choice for day-to-day sanding because it balances cut quality, durability, and value. The open-coat construction and resin-over-glue bonding called out in the product data are not just technical filler. They help the abrasive stay usable longer and keep the disc from loading up as quickly during extended sanding sessions. When you are burning through discs on repetitive prep work, that translates into less downtime and more predictable results.

The 5-inch diameter and 5-hole pattern make these a fit for sanders using that common size and hole layout. The hole pattern is there for a reason: it supports dust extraction when paired with a perforated pad, which helps the abrasive stay clearer and the surface stay more visible while you work. Less dust trapped under the disc usually means a more even finish and less chance of grinding loose debris back into the material.

Attachment is PSA, which means pressure-sensitive adhesive backing. For the right user, that is simple and secure. You get a firm stick to the pad without dealing with hook-and-loop wear, and the disc stays planted during sanding. The tradeoff is that you need a compatible PSA backup pad, so this is best for users already set up around that system rather than someone looking for universal hook-and-loop discs.

Compatibility data specifically lists Porter Cable 334 and 7335 sanders with a perforated pad, which gives buyers a clear reference point. More broadly, these Mirka sanding discs are aimed at users running a 5-inch PSA sanding setup and wanting a finer grit for finish work, touch-up prep, or smoothing between sanding stages. If that is your workflow, a 100-count box makes a lot more sense than buying small mixed packs and hoping they hold up the same from disc to disc.

Who should buy these? Anyone doing repeat finish sanding with a compatible 5-inch PSA sander. That includes woodworkers, cabinet shops, finish carpenters, auto body prep users, and serious DIYers who already know they want P320 specifically. If you need one grit that sits in the finer end of the sanding process and you want a known abrasive brand instead of bargain-bin paper, this is the kind of consumable that keeps your finish process consistent.

Mirka 23-321-320 5 in. 5-Hole P320 PSA Sanding Discs make sense for guys who already know exactly what grit they need

This is a smart buy for finish sanding when you want a known abrasive, a dust-ready hole pattern, and enough discs in the box to stop thinking about consumables for a while.

• Who it's for: Shops and serious DIY users running a 5-inch PSA sander for fine finish work.
• Why it stands out: P320 grit, aluminum oxide abrasive, and a 100-count box from a brand that actually knows abrasives.
• Worth knowing: This is not a universal fit disc. You need a PSA setup and a matching 5-hole pad to get the full benefit.

• What type of sander do these discs fit? They are made for a 5-inch PSA sanding setup with a 5-hole perforated pad.
• What grit are these discs? These discs are P320, which is an extra-fine grit intended for fine sanding and finish prep.
• What abrasive material is used? The abrasive is aluminum oxide.
• Are specific sander models referenced for compatibility? Yes. The source data lists Porter Cable 334 and 7335 with a perforated pad.