John Tracy's eyes are not green.

They're nearest in shade to Alan's pale blue, perhaps a few degrees lighter. The vibrant, unnatural aqua colour is attributable to the contact lenses, overlaying his irises with minute, impossibly fine nanocircuitry, and a brightly glowing auxiliary HUD. It's custom programming. Like most everything aboard TB5, it's been refined with his own typical touches, precisely and delicately calibrated to the movement of his eyes over the global comm module. John can process and manipulate more data with a flick of his gaze than most people can divine in five minutes, surrounded by the sphere of ever-changing information. The onboard hardware in Thunderbird 5 is only half the story, an incomplete projection of just how much information John handles at any given time.

The contact lenses (green glow non-optional) are highly specialized, there would be no sense in mass production. John owns four pairs, the only four pairs in existence. The contacts themselves were manufactured by a prototyping company in Dubai–a leading entity in the biotech industry–and made according to John's exacting specifications.

This is, very coincidentally, the same company responsible for another, highly-specialized device, designed with the same precision and delicacy, to kill John Tracy.

They are not particular about their clientele.