So compact and unassuming, they truly embody the moniker of 'More Than Meets The Eye'.
As an aside, my personal favourite is Ratbat. More on this at a later date.
I love the Japanese exclusive Autobot cassettes too, and with that said, here is a picture I that I'd wanted to take for a while:
Japanese exclusive Autobot cassettes
For those who may not know, C-116 Twincast is a repaint of Blaster/Broadcast who, like his namesake, can hold two cassettes simultaneously instead of one. His accompanying companion Steeljaw also sports an exclusive sticker, showing the schematics/weak points of their foe Mega Zarak AKA Scorponok!
The other 4 cassettes pair off and combine into two larger robots. C-121 Gurafi and C-122 Noizu together make Decibel, while C-123 Dairu and C-124 Zauru merge to form Legout.
Superb toys for an already ingenious design.