WLP011 targets German altbier specifically — a related but distinct tradition from Kölsch, sharing the same general ale-fermented, lager-conditioned approach but built around a maltier, darker, more full-bodied beer than Kölsch's pale, delicate profile.
At 65-70% attenuation, WLP011 finishes noticeably less dry than WLP029 (Kölsch) or Wyeast 2565's 72-78% ranges, leaving more residual malt character behind — a real, deliberate difference suited to altbier's fuller body and more pronounced malt backbone, built typically on Munich or Vienna malt rather than Kölsch's paler Pilsner-malt-forward grist.
Like the Kölsch strains, WLP011 benefits from genuine cold-conditioning time after a moderate-temperature primary fermentation to fully develop its clean, rounded character — skipping that step leaves the beer read as a fruitier, less polished ale than altbier tradition calls for. Altbier is WLP011's clear defining style, and a brewer building an authentic version specifically avoids substituting a Kölsch-focused strain, since the lower attenuation and fuller malt character genuinely change what altbier is meant to taste like relative to its paler, drier Kölsch cousin from the same general region of Germany. Düsseldorf's own altbier brewing tradition is the specific historical reference point most brewers building a recipe around WLP011 are ultimately trying to approximate as closely as they reasonably can.