"Max Pro Compound Cutters" include: 

• brown suede case 
• a pair of tungsten carbide curved blades in side pocket (straight blades on tool)
• an Allen key

The newly designed Max Pro Compound Cutters have a push button, when you push and turn the button it opens to 15 mm, which is good for thicker glass, ceramic & granite, porcelain tiles and stone.

Features:

• The ultimate tool designed by mosaic artists for mosaic artists.
• For Ceramic, Porcelain, Mosaic and Glass.
• Cut from 3 to 8 or 9mm glass, ceramic & granite porcelain tiles, natural and artificial stones.
• Lightweight and easy to use and handle.
• Special Hard Precision steel body.
• Replaceable 16mm Tungsten Carbide blades, Straight and Curved.
• Power Spring with shock Absorber cap.
• 3 Positions Tile Thickness Lock Lever
• Adjustable Depth Guide and Free Rotatable cutting Wheels .
• Allen key included.
• Power Spring and comfortable power handle Grips.

You can see a video of the straight and curved blades in action here 

The straight blades are used on the edge of a tile for straight cuts and the curved blades are used in the middle of a tile for a curved cut. If you want to cut circles the curved blades are the way to go.

Spare curved and straight blades are available here