I bought the wrong blades for my small rotary cutter last week.  How did I not know that there were four sizes, not three?
Fiskars Classic Loop Rotary Cutter, Hobby Lobby
Safety Story: How (not) to use a rotary cutter
Rotary Fabric Cutter Set - The WA Portman rotary cutter for fabric set includes an ergonomic rolling fabric cutter and 5 replacement blades. Great for
WA Portman Rotary Cutter Set with Blades - 45mm Rotary Cutter with Safety Lock - 5 Extra SKS-7 Steel Rotary Fabric Cutter Blades - Fabric Cutter Wheel
Fiskars Rotary Cutter - 45mm - WAWAK Sewing Supplies
4′ Sub Compact Rotary Cutter
45-mm LDH Ambidextrous Rotary Cutter - Midnight Black
Rotary cutter tips and tricks - what mistakes to avoid
The Quilters Select 45mm rotary cutter has a weighted, ergonomic grip that will make cutting fabrics easier than ever. On sale at Moore's Sewing now!
Quilters Select Rotary Cutter 45mm- an essential tool for any quilter
What size rotary cutter is best for quilting? - The Crafty Quilter
Quilting Rotary Cutters: A Complete Guide - Suzy Quilts
Best 45mm Rotary Blades for Quilting –
How to Use Rotary Cutters to Cut Fabric with Ease - Threads
History of the rotary cutter (Hail the king of cutting tools!) - Quilt Advice Tips and Tricks!