These synthetic ruby balls fill the cap of the Tempest, where they store heat and superheat the air passing between them. The set contains about 50 pieces at 3 mm, enough to fill the cap with some to spare.

Ruby is lighter than the standard zirconia, with a cap fill weight of 2.8 g against 4.1 g, and it passes heat on far more quickly. In practice that means a shorter warm-up, punchier draws and clear flavour, which is why ruby balls are a popular first upgrade.

The material is tough and holds up to repeated heat cycles. A ball retaining screen in good condition holds the fill in place, and the C-tool makes the cap's twist-lock mechanism easier to open and close.

Intended for use with: Tempest 2.