RobDog888 is right, it's based on the Range object.

The object browser is your best friend when it comes to stuff like this. If you have the referenced checked for excel in your VB project, then you can press F2 to view the object browser. You'll see a combo box that says "<All Libraries>". Select "Excel" from the combo box to see all the classes of Excel. In the classes listbox select "Range" and in the "Members of 'class' " listbox you'll see all the Range's properties, methods, collections, etc. You'll find RowHeight in there. Much easier to navigate in there rather than Intellisense.