This type of Bi-center bit mainly used for medium to medium hard compressive and abrasive formation.

Matrix body PDC bit is made by Tungsten carbide podwer , it is very high hardness material , mainly used for deep Oil&Gas well drilling.

Steel tooth drills are suitable for extremely soft formations with low compressive strength and high drillability such as clay, mudstone, chalk, etc..

Core barrel with roller bit is used in very strong rock formations(compressive strength > 100Mpa)