They might work for the wider geared axles as the 5mm width is exact. However it may not fit in some trains that use the narrower gear that is closer to 4mm wide. So not counting the clutched axle gears there are two size width for the 12 toothed gear 5mm & 4mm.
For the axle diameter I used 3 different calipers, the two cheaper ones came out at about 2.3mm and my big metal caliper showed closer to 2.5mm.
The diameter of the whole gear, 7mm is correct for both width gears.
You may want to just give them a try as they aren't that expensive but in my experience its the narrower ones (4mm) that seem to be in most trains
For the axle diameter I used 3 different calipers, the two cheaper ones came out at about 2.3mm and my big metal caliper showed closer to 2.5mm.
The diameter of the whole gear, 7mm is correct for both width gears.
You may want to just give them a try as they aren't that expensive but in my experience its the narrower ones (4mm) that seem to be in most trains