What is Class 1M Limestone? Class 1M Limestone is a premium-grade rip rap product designed for heavy-duty applications such as erosion control, shoreline protection, and retaining walls. Key Features: Material: Limestone. Size: 150mm-300mm Shape: Angular. Functionality: Provides natural appeal. Common Applications: Riverbank stabilization: Prevents soil erosion. Retaining rocks: Provides natural looking walls. Drainage control: Directs water flow effectively. Important Considerations: Class 1M Limestone is sold in bulk and bulk bags, measured by the cubic yard, or by the individual rock. Requires careful placement for maximum effectiveness. Locally sourced for reduced environmental impact.