1)sizes:13mm,16mm,19mm 2)2 to 2.5mm ... diamond pcd inserts/pdc drill bit fixed cutterGK---Our proprietary product with high impact resistance and opponent to ... drilling.And widely used for oil/gas drill bit, rock drill and coal mining drill bit. With high speed, durability, ... “The opponent to the pebble”. Characteristics1) impact resistanceIt can stand the impact more than 200 times, but the common ...