The housing is black aluminium and sealed to IP68 standards, making them suitable for underwater use. Skye guarantees sensors to a depth of 4 metres. The light collecting head utilises a UV stable polymer and is cosine corrected. The sensors have been designed with an integral amplifier to give a voltage output for use with most dataloggers, computers, PLCs, etc. All sensors are calibrated against a reference light source which is directly traceable to NPL and each sensor is issued with a calibration certificate.