The heads will accommodate any size beam from 3/4 to 1-1/2 in (19- 38mm) in widthSince beam length requirements vary widely, and they are easy for the user to fashion, we do not furnish a beamClamping device that firmly holds various attachmentsThe attachments consist of two sizes of caliper legs, two sizes of divider pointsSet of four ball points with holderOne of the large caliper legs features a joint operated by an eccentric thumb piece for fine adjustmentsA pencil may be clamped in either head in place of the caliper legs or divider points.Includes:(2) Trammel Heads, (2) Small Points, Set of 4 Ball Points and One Holder, Small Caliper Legs 6 in, Large Caliper Legs 9-1/2 in