These Globe Valves are made to fit Evergreen #224 tubing which represents 6″ pipe in O scale The small studs fit the tubing 1,8 mm/0.069″ ID.
The handwheel is 6.6 mm dia which is a scale 12″. The hole in the center is nominally about .2mm over the shaft dia. These are small enough that care needs to be taken when gluing the handwheel to the valve. Note that there is an upper and lower side to the handwheel .. the hub being longer on the lower side. I suggest you place the handwheel on it’s upper face so the long hub is facing up. Put the glue on the valve stem and insert said valve stem into the open hub of the handwheel.