Archer and Reed with a phase device
A phase device was a hand-held tool that fit over the knuckles of a person's hand and allowed its wearer to pass through matter.
One was brought to the NX-class starship Enterprise by a mysterious temporal agent named Daniels in 2151. Captain Archer used it to pursue Silik through the ship, ending up in Enterprise's launch bay, but he lost it in space when the bay doors opened. (ENT: "Cold Front")
The term "phase device" comes from the script of "Cold Front", in which the device was consistently referred to with this name.