That would be Rotary Tech, the manuf of Metal Master Rotary cutters. If your looking for their specials they can be very hard to find, as they are not listed on a "Specials" page. You just have to go to the page of prices on the family of the type cutters your interested in and see if there are some prices that are a lot lower than usual or the other prices, and thats their specials price. Sometimes buy not always they list it in red print. http://www.rotarytech.com
A frustum is a section of a cone IIRC. I have the older style and they index without the use of notches built into the inserts, and are as adjustable in a much finer graduation, but the notch type certainly has its advantages.