Goku Black Time_Ring

The Time Rings are accessories of the Supreme Kai which enable them to travel through time. They are normally used to observe future events in their main timeline.

The Time Rings have several special abilities, unlike the Time Machines created by Capsule Corporation, the Time Ring allows for "natural" time travel, and so does not create alternate timelines when used. Additionally, a wearer of a Time Ring will be granted acausality, and so even if their personal past were to be altered by someone or something- they would not be affected. As shown with the case of the original present Zamasu, as while the Zamasu from the altered main timeline was killed by Beerus due to Future Trunks altering the timeline, the original present Zamasu still continued to exist with his unaltered history thanks to his Time Ring.