NASA Clipper Duet Depth Sounder, Speed & Distance LogNASA Clipper Duet Depth Sounder, Speed & Distance Log 110mm case. 40 mm high digits. Depth below transducer, below keel, below surface. Deep and shallow alarms (audible and visual). User selectable Feet or Metres. Intelligent gain control and manual override. Selectable display rate and depth averaging rate. Depth trend indicator. No echo indicator. High transmit power. All settings stored in non volatile memory. Tactile keypad. Multilevel