This property tells you how many effects there are available. You can use the count instead of the default enumerator. For example the following code:

Set theFX = Server.CreateObject("ImageEffects.FX")
For Each theEffect In theFX
  Response.Write "<br>" & theEffect.Name & "<br>"
Next

Is functionally equivalent to:

Set theFX = Server.CreateObject("ImageEffects.FX")
For i = 1 To theFX.Count
  Response.Write "<br>" & theFX(i).Name & "<br>"
Next

Item property.