firm's Japanese-made knives. ZDP-189, a premium Japanese powdered super-steel made by Hitachi, hardened to RC 62–67, with very high carbide volume. Has excellent edge-holding ability, although it trails behind S90V and S110V in that regard. Collaborations Through the years, Spyderco has collaborated with numerous custom knife makers in the design of various models. List of collaborators Jens Anso Massad Ayoob Eduard Bradichansky Gayle Bradley Darriel Caston Peter Carrey Frank Centofante Chris Claycombe Alexandru Diaconescu Ernest Emerson Bram Frank Wayne Goddard Peter Herbst D'Alton Holder Jess Horn Michael Janich James A. Keating Szabo Laszlo Chad Los Banos Bob Lum R. J. Martin William F. Moran Ken Onion Philippe Perotti Fred Perrin Peter Rassenti Ed Schempp Ed Scott Jot Singh Khalsa Marcin Slysz JD Smith Mike Snody Brad Southard Laci Szabo Bob Terzuola Sacha Thiel Warren Thomas Ralph Turnbull Ulrich Hennicke Germany/Ulize C161GP Butch Vallotton Howard Viele Michael Walker Tim Wegner Tim Zowada Sprint runs Spyderco often produces limited edition models, referred to as sprint runs. These limited runs are generally versions of discontinued models with different blade and handle materials, though some are completely new models, such as the Kopa; a "dress knife" with several variants, each with a different handle material such as micarta, evrina, and tiger coral. Byrd brand Spyderco designs and produces knives under the Byrd brand. These knives use high quality materials and are manufactured in China, allowing much lower prices while retaining most of Spyderco's quality. To differentiate the brands, Byrd knives have a "comet" shaped opening hole in the blade, rather than the trademark round hole found on Spyderco models. To date, Byrd knives have featured 8Cr13MoV as their blade steel except for the Byrd Catbyrd titanium which uses 9Cr18Mo steel. The brand's early knives were marked 440C, but tests found that the steel was something entirely different from American 440C. This steel was closer to AUS-8 than American 440C, and also went by the name 8Cr13MoV. The first Byrd models, the Cara Cara, Meadowlark, Flight, Pelican, and Crossbill, initially featured stainless steel handles. Newer Byrds have featured aluminum, fiberglass reinforced nylon (FRN), and G10 handles. References External links Spyderco's official forum Knife manufacturing companies Companies based in Golden, Colorado