From the manufacturer:
This versatile tool instantly cuts perfect circles everytime. It's incredibly easy to use and is ideal for either a right- or left-handed user. The unique, clear base allows you to see exactly where to position the cut. The adjustable arm cuts circles from 1" to 8". It Works on paper, photos, cardstock and a host of other thin materials. Package also contains two replacement blades. Use replacement blades F9382.