Other navigational instruments and appliances: echo sounding instruments that measure water depth with sound pulses.

State frequency, depth range and transducer type; marine electronics need approvals. Measuring and survey instruments are precision goods: pack in padded cases with silica gel, state accuracy class, range and resolution, provide calibration certificates traceable to national standards, CE/BIS marks for electronic units, and keep lithium batteries under dangerous goods rules; some navigation and geophysical instruments are export controlled.