Our stone diamond core drilling bits are used for drilling all kinds of stones, refractory materials, etc. stone diamond core drill bit1, Used for : refractory materials and other hard stones2,Size: 8mm--200mm.M14,5/8"-11 Connection3,Feture:fast cutting and long life4,MOQ:50pcs5,Payment : L/C6,Packing : White carton7,Delivery time : normally 20 days8,Delivery port: Tianjin