Spectrum is Matt Trakker’s signature mask and the one the cartoon treats as the leading mask of the whole team. He wears it most often when he is flying Thunderhawk, and the fan wiki records it across most of the first season, from The Deathstone, where the team first assembles, to Raiders of the Orient Express.
What the mask does depends on who is describing it. The fan wiki gives it the control and creation of light and of any source of energy, and cites Video VENOM, where Matt uses it to turn the destructive heat of Mayhem’s machine into ordinary sunlight, and The Roteks, where it produces sound waves. Wikipedia’s character list describes sonic blasts, a short free fall that works like a glide, a laser and vision across the spectrum, and Matt-Trakker.com sums it up in a single line: if you can dream it, it has it. The glide is visible in The Star Chariot, where Matt floats from Thunderhawk across to Switchblade; the fan wiki notes that the yellow glow that should surround him is missing the first time and present the second and third.
The Kenner mask first came with Thunderhawk and returned later with Skybolt, and the toys that carry it are listed below. Wikipedia calls the Skybolt mask New Spectrum and says it makes a holographic double, while our toy record for Skybolt simply lists a Spectrum Mask, so we have not been able to tell whether the plastic differs from the first one. Matt also wears other masks when he drives other vehicles, notably Ultra Flash in Rhino, Lava Shot in Volcano and Shroud in Goliath.