圆柱头螺钉用 A级垫圈,硬度最高250HV          
          Product Grade A, Up To Hardness 250 HV, Primarily for Cheese Head Screws 
                      
          圆柱头螺钉用 A级加硬垫圈,硬度300HV以上          
          Washers: Product Grade A. From Hardness 300 HV, Primarily For Cheese Head Screws 
                      
          A级小平垫,硬度200HV和300HV          
          Plain Washers - Small Series, Product Grade A, 200HV and 300HV