I purchased my first rotary cutter (a 28mm) in the fall of 1979. These are basically round razors on handles; they allow for precise cutting of fabric, paper, cardboard, etc.
In the years since then I have purchased larger and smaller diameter cutters (they come in four sizes; which one you choose depends on how many layers you want to cut), ergonomic cutters and brands other than Olfa.
I keep coming back to the Olfa cutters because of the high quality and user-friendliness. I am especially happy with the ergonomic design – for its lock open/lock closed feature for the blade and for the fact that I can cut accurately while seated (my spinal stenosis makes standing to cut painful).
These are quality tools and well worth the expense. Be sure to purchase a self-healing cutting mat (there are many brands and sizes on the market) — this will protect and prolong the blade sharpness on your cutter as well as protect the surface on which you are cutting. — Linda Schiffer