Temporal Dial

The Time Travel Device is a wrist mounted advanced peace of technology that

allows its users to travel to different points in history.

Deadpool 2
After the death of his wife and daughter by the mutant despot Firesfist. Mutant soldier Cable suedes the Time Travel Device to go back to the point in time when Firefist was a teenager and kill him. Thereby erasing the deaths of his family and saving his future from this doomed reality. However Cables plans were repeatedly interrupted by the mutant mercenary Deadpool and after numerous violent encounters the two teamed up to stop Russell from going down a dark path and succeeded but seemingly at the cost of Wade’s life. Unwilling to let Deadpool die Cable went back in time to a few hours before they confronted Russell and managed to save Deadpool but sacrificing his last charge.and keeping his from returning to his wife and daughter.

Later Wade had Yukio and Negasonic Teenage Warhead fix the device allowing him to save his girlfriend Vanessa from death along with fellow X-Force member Peterand even killing his Weapon 11 self in 1973 before he could attack Wolverine.

Functions
The device allows it users to travel in any point in history. However as Cable mentioned the further in time one goes back the less precise the location it will allow it user to land. Initially the device also only had two charges which allowed the user to go back in time and return to their original time although Yukio and Negasonic seemed to have fixed this as Wade later made several jumps in time with the device with no worries of this.