I have or have had pretty much the entire series so let me see if I can sum it up. Have to work from memory though because I'm away from home.
In chronological order:
GYIAT101-102: made by Alps. Old logo. Dyesub PBT caps, SKCM Salmon. Winkeyless.
GYUM97SK: made by Silitek. Old logo. Dyesub ABS, SKCM Black/Early. Winkeyless. Includes a 160 g steel weight.
GYUM95SK: made by Silitek. New logo. Lasered ABS, SKCM Black/Late. Winkeyless. Includes a 160 g steel weight.
GYUM90SK: made by Silitek. New logo. Lasered ABS, SKCM Black/Late. Has winkeys.
Note that the early black Alps are way better than the late ones, and feel and sound more like salmons. They're great to type on, so much so that I made a video about it:
Essentially you want the GYI ones, or GYUM97SK. Hope this helps
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