Similar to a plankton net in shape, this bag will collect any invertebrates within the sample area. The downstream side has a net bag fitted with a closed, screw on filter. The upstream side is sealed with a large upstream filter of preferred size to prevent any invertebrates entering the sampler through drift or when the external substrate is disturbed. For use on harder substrates, the Hess Sampler is also available with teeth for cutting into the substrate, effectively converting the sampler into a cylindrical corer or stovepipe sampler. Two strong handles allow for forcibly pushing and rotating the cylinder into the stream bed. The base of the Hess sampler is pushed into the substrate to make a seal.

The Hess sampler is used in similar circumstances to a Surber Sampler but is even more accurate.