【Dual-End Hardness Design】 Each hardness pen features writing needles with different hardness levels at both ends. The Mohs hardness scale pairs are: 2&3, 4&5, 6&7, and 8&9. 【Quick and Easy Scratch Testing】Simply select the pen, slide at a 70° angle on the surface, and check for scratches; Enables fast on-site hardness checks or visual comparison under a magnifier for accurate results. 【Durable and Ergonomic Design】Made with materials for long-lasting use; Comfortable grip and sturdy construction ensure reliable performance for both professionals and hobbyists. 【Portable Kit】Includes 4 mohs hardness picks (Mohs 2-9) and 1 aluminum alloy case 9.06 x 7.28 x 1.85 inches/ 230mm x 185mm x 47mm for organized storage and easy carrying; Perfect for jewelry appraisal, geology fieldwork, classroom teaching, and home hobby projects. 【Wide Application Range】Effectively tests gems, jade, tiles, flooring, glass, phone screens, minerals, concrete, and more; Covers hardness levels 2 to 9 for versatile use across various surfaces.