
Hy-3 30PCS Surface Roughness Comparator Blocks 6 Machining Processes Standard Sample Plate Ra Value Gauge for CNC Machining Surface Quality Check. Includes comparison samples for turning, vertical milling, horizontal milling, plain grinding, external grinding, and flat lapping, making one set suitable for various applications. Each specimen is manufactured with precise surface finishes, providing reliable and repeatable roughness comparison for quality control. Enables quick comparison by sight and touch without requiring complex measuring equipment, improving inspection efficiency. Made from high-quality steel with excellent durability, ensuring long service life and stable reference accuracy. Compact notebook-style case keeps all samples organized, protected, and easy to carry for workshop or on-site inspection. Widely used in CNC machining, metalworking, mold manufacturing, automotive, aerospace, and precision engineering industries. Provides an economical and practical method for routine surface finish evaluation, reducing inspection time and equipment costs.