The B60 Super Blower was designed for use in long underground single bore conduit from 2-1/2" through 6". The B3000 Power Unit must remain above ground for safety reasons, and the 2-1/2" diameter x 25' long hose and seal-off are used in the manhole. The portable triple motor power unit provides a high volume of air to blow a line in large bore conduit whether above ground or below ground.