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