(There's no video for Expo '99 Icons yet. Please contribute to MR and add a video now!)
Expo '99 set include 19 icons representing products that were shown at that expo conference.
Expo--99---Set.sit (74.45 KB)
Expo '99 Set icons / compressed w/ Stuffit
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Those are classic Mac OS icons.
Emulating this? It should run fine under: SheepShaver