The Shrink Ray is an item in Size Matters. It is a remnant of technomite society which can be used to shrink and expand objects. Ratchet and Clank obtained the device from the Skyboarder in "Win the skyboard race" taking place near the Mechanoid Factory on Kalidon. After obtaining it, they used the device on many occasions to access restricted technomite areas, as well as locations that were otherwise too small for Ratchet to access. He also used it to enter Clank's insides in the mission "Defeat all Technomites". During "Defeat Otto Destruct", Captain Qwark is manipulated into taking the device from Ratchet and Clank, so Otto Destruct can use it as a weapon against them. As a result he used it to grow himself to a size large enough to combat Giant Clank.
Among the uses of the Shrink Ray were Grind Locks, small locks that could be accessed by using the Shrink Ray. Once inside a Grind Lock, Ratchet used grindboots to navigate a grind rail, and hit various targets along the way to disable force fields blocking the path. The objective was to get to the end of the grind rail without losing all nanotech (although the nanotech when shrunk does not correspond with that when of a normal size), by dodging or destroying obstacles, switching rails, and passing force fields. If completed successfully, the lock would be unlocked and the door would open, and Ratchet would use the Shrink Ray to return to his normal size.