This grab is intended for use in soft sediment. When the grab touches the bottom, the trigger is pushed using a messenger and the grab closes, collecting the sample. 

The grab locked in open condition and lowered through the rope to the sediment bed. A messenger is dropped through the rope to sampler top and shut the bottom shutters to close. 

Upon retrieval, the top doors can be opened to collect the sediment sample. This sampler is preferred for collecting soft sediment from calm regions like lakes, ponds etc,.