Height size is based on overall height.
 
Normally this means the Capital letters are the exact size selected.  But when the letterstyle has letters that drop down or raise up, keep in mind the height selected will be the overall height. 

Example: 

What if you want something custom (ie - wavy, arched, mirrored)?  No problem.  After you order, email us the change (ie - "be sure to make the letters exactly...") and we'll be glad to make the change.