Extensions can be with or without attached helical shaped steel plates.  Each standard helical steel plate is 3/8-inch (10 mm) or 1/2-inch (13 mm) thick and has an outer diameter ranging from 6 to 15 inches (152 to 381 mm), and an inner annulus either 1-1/4, 1-1/2 or 1-3/4 inches (31.7, 38 or 44.5 mm) square, or round to accommodate 2 7/8″, 3 1/2″ or 4 1/2″ pipe.  Larger and custom sizes available.  Each plate is formed with all radial sections normal to the central longitudinal axis, 3 degrees.  The helix pitch is 3 inches (76 mm).

The central steel hub of lead sections and extension sections is round cornered square (RCS), solid steel bars.  RCS bars include 1-1/4, 1-1/2 or 1-3/4 inches (31.7, 38 or 44.5 mm) square

MacLean/Dixie anchors are available in single, double, triple and quadruple helix configurations. Helix sizes and bar sizes may be custom ordered in any combination as required for application. Standard MacLean/Dixie extension bar lengths are available in 3 1/2-, 5-, 7- and 10-foot lengths.