Diamax BPA40 4″ Aluminum Backer Pad

The Diamax BPA40 4″ Aluminum Backer Pad is a professional-grade backing pad designed to provide stable, durable support for polishing, grinding, and sanding pads on angle grinders, air polishers, and other polishing machines. Constructed from rigid, high-quality aluminum, this backer pad ensures maximum stability and minimal flex, making it ideal for straight-edge polishing, surface finishing, and detailed edge work on stone, tile, engineered stone, and other hard surfaces.

Its 4-inch diameter strikes a perfect balance between coverage and precision, allowing operators to maintain consistent pad contact while working on flat surfaces, edges, or small areas where precision is critical. The rigid aluminum construction also provides long-lasting durability, resisting wear and deformation even under heavy-duty use, while maintaining smooth, vibration-free operation for superior finish quality.

The BPA40 features a standard 5/8″-11 threaded arbor, ensuring easy mounting and secure attachment to most angle grinders and polishing equipment. This allows for quick tool changes and reliable performance in demanding fabrication, installation, and finishing workflows.

Designed for both wet and dry applications, the Diamax BPA40 provides consistent performance when polishing granite, marble, quartz, porcelain, and engineered stone surfaces, making it an essential tool for stone fabricators, countertop installers, and restoration professionals. Its rigid support ensures even pressure distribution, reducing the risk of low spots, uneven finishes, or chatter marks, and enabling professional-quality results on every project.

Key Features

• 4″ Diameter – for precision polishing and finishing.

• Aluminum Construction – provides strength and durability.

• Hook & Loop Backing – allows quick and secure attachment of pads.

• Standard Thread Size (5/8″‑11) – fits most grinders and polishers.

• Ideal for Straight-Edge Polishing – on flat surfaces.

• Max RPM ~3,500 – suitable for typical polishing speeds.

Specifications