Simple and sharp - a rotary cutter in your sewing toolbox is great for when you need to accurate in your cutting.  Perfect when making your own bias binding or when cutting out patterns in slippery/delicate fabrics.  

When cutting fabrics, you will need to protect the surface below, such as using a cutting matt or old board

Can be used by both right and left hand by simply turning the safety cover around. Cuts beautifully regardless of how you hold it, whether held upright or at an angle as the cover opens at a tilt, due to the wide cutting range with just the right amount of blade exposed.