Version 4.0 of the Pencil beam scatterometer Wind Processor has been released. As compared to previous release 2.2, PenWP version 4.0 can process data from the Haiyang-2B/C/D satellites. The new NSCAT-4DS Geophysical Model Function is included for improved consistency between Ku-band wind retrievals and C-band wind retrievals and buoy winds. Sea Surface Temperature dependent adjustments to the backscatter can be applied to reduce wind speed biases. Improved and New Quality Control flags have been introduced. The backscatter calibrations have been tuned for the generation of climate data records from QuikSCAT, RapidScat and Oceansat-2. See the PenWP pages (https://nwp-saf.eumetsat.int/site/software/scatterometer/penwp/) for more information. PenWP is a OSI SAF software.