To be valid, objectvar must be an object type consistent with the object being assigned to it.
The Dim, Private, Public, or ReDim statements only declare a variable that refers to an object. No actual object is referred to until you use the Set statement to assign a specific object.
Generally, when you use Set to assign an object reference to a variable, no copy of the object is created for that variable. Instead, a reference to the object is created. More than one object variable can refer to the same object. Because these variables are references to (rather than copies of) the object, any change in the object is reflected in all variables that refer to it.
Dim fso, d, s
Set fso = CreateObject("Scripting.FileSystemObject")
Set d = fso.GetDrive(fso.GetDriveName(drvPath))
s = "Drive " & UCase(drvPath) & " - "
s = s & d.VolumeName & "<BR>"
s = s & "Free Space: " & FormatNumber(d.FreeSpace/1024, 0)
s = s & " Kbytes"
ShowFreeSpace = s