Sea Master 400 is a non-rotating, four faced S-band (NATO E/F-band) volume search radar designed to simultaneously provide air surveillance, helicopter control, surface surveillance and weapon control functions. Drawing on technology previously proved in Thales’ SMART-L, SMART-S Mk 2 and APAR radar systems, Sea Master 400 uses active phased array multibeam technology to enable the concurrent provision of situational and critical awareness through a single highly automated mode of operation.

Exploiting proven multi-beam and Doppler processing principles, Sea Master 400's advanced system architecture delivers simultaneous functionality at high update rates regardless of environmental and clutter conditions. These include large search volume with high elevation coverage, reliable detection of small targets, rapid automatic track initiation, low false alarm rates, and helicopter detection and approach control.

Sea Master 400 has been specifically engineered for installation in an integrated mast structure. Its four faces provide unrestricted coverage, while the hardware design allows for easy accessibility for maintainers inside the mast, so promoting a high Mean Time To Replacement and limiting the exposure to external hazards. Sea Master 400 is known as SMILE in the IM400 systems contracted by the Royal Netherlands Navy.