If you could kindly tell us your required diameter and local stratum(there is rock or not), we can recommend you suitable drill bits.
we can provide different size bits, from 75mm to 500mm diameter size. made by alloy, used on sand and soil and soft rock.
Three wing alloy bit features:
3-wing drill bits connects with adaptor which connects with drilling rods, it is sharp in the end, very easy to penetrate soft drilling mediums.However, it greatly enhance opening hole drilling efficiency.
The connect pipe is hollow as shown in the picture, so that the mud can reach. The purpose of mud is to carry the drill cuttings to the surface, to prevent too much friction between the bit and the drilled surface(to prolong the life of the bit), and to provide hydrostatic pressure against the hole to prevent collapse.