My used but pristine Fletcher 2100 mat cutter is on the way. I will need blades for the cutter and looking at what is available I see there are a few to choose from. One of the blades is just listed as "Mat Cutting". The others are Super Keen .012" and Super Keen .015". I know that the last two are for cutting mat board of different thickness, the .015 for heavier 8 ply and the .012 for 4 ply. Will I need the "Mat Cutting" blade for making the beveled window cut? What is that blade for?

http://framingsupplies.com/Fletcher/Fletcher2100.htm

The link is to a page showing the options available, but I can't find a description of what the blades are used for.

Thanks,

Ben