The Bracket is a huge cosmic wall that surrounds the entire Ring System of Eternity. This wall is impossible to penetrate, and you can only go through it using extremely complex instant travel ships that even DeltaTech cannot manufacture.
The Bracket appears to be a huge, red wall of sorts that resembles a spider's web. There are occasional holes in The Bracket, but don't be fooled. These holes, if you enter them can completely glitch you out of reality and corrupt your existence state, bringing them to impossible values, therefore trapping you in Unexistence.