He has a perception filter.
Heh, well, the colour gives it away, especially the clear transparent fist and arm gun (which are transparent purple on Shockwave).
This is a bit embarrassing, but I've been sorting out Cyber Planet Keys to match them up with Cybertron figures, and have only just realised that the first letter of the code represents the size class: s for scout, d for deluxe, etc
Reveal the Shield Deluxe "G2 Laser" Optimus Prime has the Matrix sculpted inside his chest.
Heh. I'm not sure if I really have only recently noticed it, or maybe I noticed it before then forgot about it. Gah.