This Back Light Boom attaches to the shaft of most lightstands with diameters of 19 20 25 28mm. The top tube diameter: 25mm 3 sections boom arm complete with Pivoting Clamp 124 Counter Weight G-Peso 023 cable clips and locking key. The ful assembled length is 200cm. Attaches to shaft of most lightstands with ø of 19 20 25 28mm Three sections max extension to 2.1 m (6.5') Dismantled length is 71cm (28 inch ) for ease storage or transport Supplied with counterweight This product has a safety payload of 3kg Specifications Weight: 7.01 kg Payload: 3 kg Boom Min Extension: 120 cm Boom Max Extension: 210 cm Arm Tube Diameters: 25 mm Load Capacity At Maximum Extension: 3 kg Top Attachment: 1/4? screw 3/8? screw 5/8? (16mm) stud Colour: Black Material: Aluminium Sections - Boom Arm: 3