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.