With modern drilling equipment, it is now possible, in suitable conditions, to drill smalldiameter holes from top to bottom of the face, and where this can be done considerable advantages as to cost and efficiency can be obtained as compared with the bench method. In high faces of 50 ft (15 m) and upward it is not always easy to drill vertical holes to give small burdens because of the breakback of the rock at the crest of the quarry face. It is therefore recommended that larger burdens be taken and that the vertical holes be supplemented by breast holes at quarry floor level. These holes are intended to permit concentrated explosive charges to blow out the toe rock, while the explosive in the vertical holes brings down the rock from the face.