This Manfrotto 237HD Heavy Duty Flex Arm is 18mm in diameter,
wider than the standard Flex Arm. Otherwise, it shares the identical
feature set: 21.1" (55 cm) in length with a 5/8" hex stud to affix to
the Super Clamp 035 and has a 3/8" female thread and 1/4" 20 male end.