Rin and Len's Append voicebanks fixed a lot of problems that both of their previous releases had. Both Rin and Len had 3 separate voicebanks to create expressive singing. Both had "Power", a strong and clear voicebank. Rin had "Sweet" and Len had "Serious" which were meant to be softer vocals. And then they had "Warm" (Rin) and "Cold" (Len) to naturally fill the gap between their respective voicebanks. Unfortunately, in order to successfully install and activate their appends, you need to have bought their ACT2 software. You'd be unable to use them with out it. You could not install them successfully with just their original package either.