Diamond core drill bit 1.OEM product,competitive price 2.offer faster penetration and long life 3.good quality,fast drilling Diamond core ... and granite stone3.good quality,fast drilling speed 30mm/minapplication:1.for drilling glass, concrete,ceramic, marble and granite stone, ... also provide other size,please free to contact us. 1-3/8"diamond core thin wall dril bit for concrete,asphalt drilling