Dave, I have the same BS100, tho mine is sporting a red grip.
On our old site, before the crash, I had posted it. I think we all came up with a "bearing seal" tool. Thus the BS part designation. Perhaps used to pry out a seal in a typical drum brake application, and that would explain the curvature to wedge over the lip of the drum. Seems it might work better for deeper set seals, perhaps even rear axle seals on 3/4T trucks.