The Butterfly discs are high tech carbon fiber with diamond or aluminum oxide for extremely fast cut while being extremely tough.
Purple Butterfly. Diamond. 20mm x .3mm extremely fast cutting on all rocks and ceramics. 5 discs for $20.
Orange Butterfly. Aluminum Oxide. 22 x 0.25mm for all metals. Extremely fast and tough. Cut silver, gold, steel, titanium. 10 discs for $20.
The Whisc disc is a very sturdy diamond disc that cuts extremely fast and smooth with very little heat. 20mm x 1.5mm thick
You need to mount these on a good mandrel to take advantage of these discs.