Provides L2 high resolution (HR) short time critical (STC; 36-hour latency) altimetry from the Poseidon-4 SAR altimeter on the Sentinel-6B spacecraft. It contains Sea Surface Height (SSH), Sea Surface Height Anomalies (SSHA) and Significant Wave Height (SWH), along with 1 Hz Ku-band measurements processed from L1B altimetry including the range, orbital altitude, time, and water vapour. It also includes altimetry corrections, significant wave height and wind-speed from the AMR-C. This release is reduced to exclude the 20 Hz observations that are included in the standard product. The S6B STC product is analogous to the Jason-3 IGDR product.