BigChamp
From Retrobike Wiki
Koga's BigChamp is a very strong, nicely finished fork. Built by Miyata. It uses Miyata's own Hardtlite FM-1 steel tubing. The BigChamp is no featherweight.
Succeeded by the also strong, but much lighter Miyata FatMax Aluminum.
The particular BigChamp shown in the pics belongs to the 1991 Koga TrailRunner.