tl;dr: Ultramarine 1 Flash is an open model fine-tuned from GLM-5.3 Flash, targeting professional knowledge work in finance, law, consulting, and operations. It scores 59.3 on the makers' internal PI Knowledge Work benchmark at $0.13 per task—beating Claude Fable 5 and GPT-5.6 Sol while coming within three points of Claude Opus 5.5 and GPT-6 Sol at a fraction of the cost. API pricing matches the base model at $0.15/$0.50 per million input/output tokens, and it generates 6.5% fewer tokens than its base.