A new drill hole pattern in which two overlapping holes of diameter about 2-1/4 in (5.7 cm) are drilled in the tunnel center and left uncharged. These holes form a slot roughly 4 in by 2 in (10.2 cm by 5.1 cm) to which the easers can break. All the holes in the round are parallel and in line with the tunnel. Short-delay detonators are used for the easer holes and 1/2-s delays for the rest of the round. A pull of 10 ft (3.0 m) per round has been obtained in strong rock with 10.5-ft (3.2-m) holes. Explosive consumption for the easer holes is about 0.2 lb/ft (0.3 kg/m) of hole.