They say the best things come in small packages, that could not be more true for Pet Fox’s new single “Swerving.” The Boston-based trio packs a lot of surprises into the one minute and twenty-three-second song: a somewhat disjointed compilation of acoustic and electric guitar strains are held together by a solid drum rhythm as they rage beside warm vocal harmonies. The summery vibe of the single comes from the group’s tendency to permeate its indie rock with ‘60s pop overtones, but the edge comes from its math-rock understanding. “Swerving” is a preview of the group’s upcoming record Rare Occasion out everywhere July 19th. The band will be playing ONCE in Somerville on July 24th, and we are streaming “Swerving” to keep its sizzle going. – Rene Cobar