Specification: Efflux Index (Flow Coefficient of Fine Aggregates) apparatus is used to obtain information about the shape and the angularity of grains of fine aggregates. The flow coefficient of an aggregate is the time, expressed in seconds, for a specified volume of aggregate to flow through a given opening, under specified conditions using a standard apparatus. Efflux index (flow coefficient of fine aggregates) apparatus consist of two funnels with different opening, cylindrical hopper, metal stand with a shutter and metal container.