The purpose of the top or bottom Lateral (distributor and collector) assembly is to collect or distribute a uniform flow within the media, and especially designed for intermediate collection or distribution in mixed bed process. The efficiency of such a design can be applied to backwashing or regeneration.

These are mainly used for:
 Industrial softeners and demineralisers
 Ion exchange for food processing
 Chemical and pharmaceutical catalytic exchanges
 Petrochemical processes such as sand and clay filters, MEROX, MTBE etc