The Backpack Time Traveling Device has recently gone through its third
stage of development. It consists of tubing, wiring, and live mice.
The backpack is worn, and has a switch which hangs on the belt.
Once the switch is flipped electricity utilizes the life-forces of the
mice to send the adventurer back in time. Two mice are needed per
trip, and the backpack can only be used once (preferably to correct
a misfortunate event). A keypad is mounted in the lower section,
though the adventurer needs a certain character code to be able to
activate the backpack.

Professor Penelope