Eight 5-cm-aperture, 15-m-Iong dipole magnet prototypes have been produced and cold-tested at Brookhaven National Laboratory (BNL) and Fermi National Accelerator Laboratory (FNAL) under contract with the Superconducting Super Collider Laboratory (SSCL). These magnets are the last phase of an R&D program aimed at demonstrating the feasibility of the 5-cm-aperture designs developed by BNL and FNAL. They are also usedThis work is supported by the U.S. Department of Energy under contract No. DE-AC35-89ER40486.as vehicles to transfer technology from the National Laboratories to the collider dipole magnet contractors. The BNL magnets, which rely on an horizontally-split yoke, and the FNAL magnets, which rely on a vertically-split yoke, perform according to their somewhat different mechanical designs and have equally successful quench performance.* Kapton® is a registered trademark ofE.I. DuPont de Nemours & Co.a The number and !be number in parentheses correspond respectively to tile mean and tile standard deviatioo. For DCA2XX magnets, the eod-collars are DOt taken into 8CCOOIIl