The volume and concentration are lot specific.
Examples below:
Lot: 6J30L72900
Volume: 23.6 µL
Concentration: 1.06 mg/mL
Lot: 8A10L72900
Volume: 22.9 µL
Concentration: 1.0917 mg/mL
The concentration of the newer lots should be on the vial label. The volume can then be calculated using the lot specific concentration and the pack size, which is 25 µg.