Manitowoc 4100W Ringer Crane #27 and #22A Boom Extension Kit with #123 Jib. Functions / Features OF BOOM EXTENSION KIT: 5 - 40 foot boom sections. 1 - 40 foot mast section. 1 - 20 foot mast section. FUNCTIONS / FEATURES OF #123 JIB:. 16 pendant line sections. Strut support lines for 0 degree jib angle. Strut support lines for 10 degree jib angle. Strut support lines for 20 degree jib angle. 4 gantry/backmast support lines. 4 counterweight tray/backmast support lines. Hardware pack for assembly.