this Manfrotto Spring Clamp attaches onto bars up to 40mm giving an attachment for lighting accessories. This replaces the Manfrotto 2936. Attachment (bottom): type 17; attachment 2: type 1; clamp range - max. (round tube): 1.57 in.; clamp range - min (round tube): 0.20 in.; color: black; length: 6.14 in.; material: steel; weight: 0.71 lbs.