Probably one of the more interesting times in Spyder history is when they elected to use ATS-55 as their main blade steel for all their high end Japan made blades. It was a brief but interesting era needless to say and some of the blades made with ATS-55 are getting quite desirable for collecting.
Some of the better known icons of that era are the C-44 Dyad, C-39 Dyad Jr., The G-10 Harpy, The original G-10 Police, The Rookie, ect, ect,. It also took place in what I personally refer to as the Golden Era of Spyders (1998-2003). What was very interesting to me about ATS-55 is that I don't recall any other production knife company ever using the blade steel here in the USA. It was probably the shortest of all the blade steel tenures during Spyderco's growth as a company but still produced some of the more interesting classics.
Personally I always liked the steel myself however not quite as good as I do VG-10. But it was still a much better blade steel than a lot of production knife companies use today. It sure had a wicked edge on thinner blades like the plain edged blade on the big C-44 Dyad for instance and it also seemed like it held up extremely well on Spyderedged blades as well.
Let's talk about the ATS-55 era, it's models that came forth and why it was so obscure in the production knife world.