If you currently have 1.100 or less delay leaving on the top bulb with a full tree, you won't have any delay on a .4 pro tree.
If you run a class that uses a .5 pro tree, you can use the box if you have more than 1.000 delay.
As an example: let's say if you have 1.060 on a full tree, you'll use .060 on a .5 pro tree......
If you use 1.130 on a full tree, you'll use .030 on a .4 pro tree and .130 on a .5 pro tree.....in theory.
Johnny