... for cooling. 3.Longer usage life diamond drill set Diamond core dril is for dry drill at wall,concrete,reinforced conc ... better performance,using water for cooling.Comprising of:1. 5pcs core drills: Ø38x150mm, Ø52x150mm, Ø65x150mm, Ø117x150mm, Ø127x150mm2. 5pcs aceessorieshex adaptor 90mm,SDS ...