These rulers are used in all of Trudie's workshops and are demonstrated in all of her books. You can order them from toll free number - 1-888-305-4847 (This is the number for Patched Works). Here are Trudie's Rulers:

 

Big Daddy™ is 24" by 6 1/2" -$17

  

Big Mama™ is 6 1/2" by 12" - $14
Rotary Rule™ is 3 1/2" by 24" $14  

Rotary Mate™ is 3 1/2" by 12" -$10

The Rotary Mate is part of a cutting system.  It is intended to be used with my Rotary Rule ruler.  It is quite usable by itself.  A smaller ruler is great for cutting small measurements and doing any trimming, etc.

 

There are two sets of number on the ruler.  The numbers in the center are when it is used independently.  The ones further down, are adding onto the Rotary Rule making a 7" ruler altogether.

 

Along one side are "Speedies".  These triangles are used when a pattern is calling for a section to be taken off a shape, leaving behind the proper seam allowance.  I make snowball  blocks this way and other designs as well. 

 

This ruler is in many illustrations in my books (14 books altogether) and shows you how it is actually used.