All Sabre trucks now come with Sabre's own custom urethane pivot cups.
Designing these specifically to fit Sabre trucks these are super-precise fitting pivot, which means less slop and a smooth turn, even on cast hangers.
For 2018 Sabre are using a new injection moulding method, which allows tighter tolerances and a better finish over the previous hand-poured pivots.
Pivot cups are the single most important part of your trucks, and possibly your whole board. Worth the upgrade if you're running the old ones!