Mirka OSP-4 Finishing 4.5" x 5" Plain is a finishing pad for surface preparation and final sanding work. This is a finishing pad designed for sanding and refined surface prep before the next coating step. Model Number: OS-127-004. It is part of Mirka's Optimized Surface Preparation system and is positioned as step 4, where the goal shifts from shaping and leveling to getting the surface ready for a cleaner final result.

What matters here is where this product sits in the process. A finishing-stage abrasive is not about aggressive removal. It is about cleaning up the previous sanding steps, refining the scratch pattern, and helping you move toward primer, top coat, clear coat, or final paint correction with fewer surprises. If you are working through a structured refinishing process, using the right finishing pad at the right point saves time compared to trying to force a rougher abrasive to do cleanup work it was never meant for.

The 4.5 inch x 5 inch plain format gives you a compact working size that is easy to control on smaller panels, edges, repair zones, and detailed prep work. That matters in automotive refinishing, marine repair, and paint prep because consistency is usually more important than raw surface coverage. A pad this size is easier to keep flat and easier to manage when you are chasing a uniform finish instead of trying to remove a lot of material quickly.

Mirka lists this product for use on gel coat, lacquers, clear coat, UV primer, primer, top coat, steel, paint stripping and removal, plaster and filler, aluminum, plastics, paint sanding, and body filler. That broad material list makes it useful for collision shops, paint departments, composite repair, and general refinishing benches where one finishing abrasive may need to move from filler refinement to primer prep to painted surface sanding.

The plain backing style is important if your setup or sanding method calls for a non-perforated pad rather than a hole pattern. For buyers already working inside the Mirka OSP process, that keeps product selection simple: you are choosing the right step, the right size, and the right backing style for your established workflow instead of mixing unrelated abrasives and hoping the finish comes out clean.

The 200-piece pack quantity is another practical point. This is not a casual one-off purchase. It is aimed at users who go through finishing abrasives regularly and want consistent supply on hand for repeated jobs. If your work involves prep on painted panels, primered parts, fillers, plastics, or coated metal, buying in box quantity reduces downtime and keeps your finish process more consistent from job to job.

Who should buy it? Shops and serious users who already understand staged sanding and want a finishing pad that fits a defined system. If you do automotive refinishing, body repair, marine gel coat work, paint prep, or composite surface finishing, the Mirka OSP-4 Finishing 4.5" x 5" Plain makes the most sense when you need reliable step-4 sanding rather than general-purpose abrasive guessing.

Mirka OSP-4 Finishing 4.5" x 5" Plain keeps the last sanding step predictable

If you already work in a structured refinishing process, this is the kind of finishing pad that helps you get cleaner, more repeatable results without overthinking abrasive choice.

• Who it's for: Body shops, paint techs, marine repair users, and serious refinishers who want a dedicated step-4 finishing abrasive.
• Why it stands out: It is built around a defined Mirka process, covers a wide material range, and comes in a 200-piece box that suits real shop volume.
• Worth knowing: This is a plain 4.5 inch x 5 inch finishing pad, so make sure that size and backing style match the sanding method and workflow you already use.

• What is this product used for? It is used for sanding and finishing-stage surface preparation as step 4 of Mirka's Optimized Surface Preparation system.
• What size is the pad? The pad size is 4.5 inches by 5 inches.
• What materials is it suitable for? Mirka lists gel coat, lacquers, clear coat, UV primer, primer, top coat, steel, paint stripping and removal, plaster and filler, aluminum, plastics, paint sanding, and body filler.
• How many pads are in a pack? This part number is sold in a 200-piece pack.