Hexatronic MPB30611/12 (Millennium part 637292) is a 120-piece pack of 3.5 mm test darts in TIA color coding, ten each across twelve colors, for proofing microduct before fiber is jetted. Sending a dart through each duct confirms the bore is clear, continuous and free of collapses or debris that would stall a blowing shot halfway to the next access point. Matching TIA colors to duct numbering lets a crew verify and document every path in a 12-way bundle without confusion. Cheap insurance against a failed blow on a production FTTH microduct build.