US-04 sits between US-05's clean American restraint and S-04's more overtly English fruitiness — Fermentis markets it specifically as an English-style option for American ale, a real middle-ground product for a brewer wanting slightly more character than US-05 provides without committing to a fully English-profile strain.
At 73-77% attenuation, US-04 finishes a touch less dry than US-05's 78-82% range, leaving marginally more body and residual malt character behind. Medium-high flocculation gives it solid, reliable clearing behaviour, similar in spirit to S-04's own fast-clearing reputation, though without quite the same premature-flocculation risk S-04 carries at the cool end of its range.
American-style ales wanting a rounder, slightly more traditional edge than a purely clean strain provides are US-04's natural fit — a brewer who's tried US-05 and found it too neutral for a particular recipe, without wanting to jump all the way to a fully English strain like S-04, has a real reason to try US-04 as the in-between option instead. Rehydrating before pitching is optional rather than required with this strain, and either approach rewards the same low-fuss handling most Fermentis dry strains give a homebrewer across an ordinary standard-strength ale recipe built specifically and deliberately around it right from the very start.