SR-6

The SR-6, more often referred to as just the Shrink Ray, is, as the informal name implies, a prototype shrink-ray device designed by a top-secret East Asian laboratory. The weapon can shrink any object to the size of an apple.

Lore
The SR-6 shrinks something to a constant size; possibly the only person to take note of this is Dr. Nefario, and by observing the objects that had been shrunk by the SR-6 in Gru Labs, he discovered that the shrunk state of an object isn't permanent. Nefario discovered that the greater the mass of the object, the faster the shrunken item grows back to normal size. This is an effect called the Nefario Principle, named after Dr. Nefario who is the first to describe the effect properly.

The SR-6 may use a radioactive material to power it. In order to fire the shrink ray, one must either press a button on the ray itself or another button from a control panel.