Tender For supply of outer drill tube type 55 dia 42.5 x 32mm total length 1720 mm (outer tube) with 4 start internal thr , inner tube type 55 dia 30x28 mm total length 1750 mm (inner tube) with ejector slots for precihole d , type 45 drill tube dia 17 x 2500 mm oal thread on both end to drill head dia 19.4mm