||A miniature version of the ECO Triplet sensor. It is a three-optical-sensor, user-defined instrument that is designed for use in AUVs, gliders and profiling floats and carries any combination of single-wavelength fluorometers or scattering sensors. ECO Pucks are real‐time only sensors as they are integrated onto the OEM platform that provides power and data handling. The fluorometers can be configured (with typical sensitivities) for chlorophyll (470/695 nm, sensitivity 0.015-0.025 ug/l), FDOM (370/460 nm, sensitivity 0.184 ppb), phycocyanin (630/680 nm, sensitivity 0.086 ppb), phycoerythrin (520/595 nm, sensitivity 0.086 ppb), uranine (470/530 nm, sensitivity 0.073 ppb) or rhodamine (520/595 nm, 0.086 ppb). The scattering meter can typically measure optical scattering at blue, green or red wavelengths (412, 470, 532, 650, 700 and 880 nm, sensitivity 0.002-0.003 m-1).