Ant-Man Suit
A costume designed by Hank Pym to allow the wearer to safely use Pym Particles to alter their own size.
The original suit was created in the 1970s, when Hank Pym was an Agent of S.H.I.E.L.D, and he has been improving on the technology ever since.
A version of the suit was stolen by Scott Lang, which was revealed to be a set-up by Hank, who wanted Scott to become the new Ant-Man.