Grinding wheels for stone or masonry, tested in German EN12413 standard and fit RoHS and PAHs. Features: 1) Dimensions: a) 4" x 1/4" x 5/8" (100 x 6 x 16mm) b) 4-1/2" x 1/4" x 7/8" (115 x 6 x 22.2mm) c) 5" x 1/4" x 7/8" (125 x 6 x 22.2mm) d) 9" x 1/4" x 7/8" (230 x 6 x 22.2mm) 2) Product specification: C24RBF the meaning of C24RBF 80m/s a) C24: oxidation silicon materials grit 24 b) R: harness grade c) B: combined material 'resin' d) F: fiber glass reinforced e) 80m/s: rpm, means meter per second, rotary speed 3) Characteristics and applications of discs: a) Applications: general purpose disc for stone working, b) Nets in bottom side of the disc c) Characteristics: standard quality, made of normal grade corundum, medium hard bond, flat type black color, high speed 4) Operation description: a) We must operate the discs correctly, or they will make dangerous to us. The discs should be mounted with the flanges very tightly. The workers should operate the discs with safeguard b) The discs are for metal or stone applications, and we should use them for right applications c) To use suitable hand tools for operation of different sizes discs, with different ampere currents