This extra pre-filter captures a large portion of coarse dirt before the water reaches the actual aquarium filter (external filter). The pre-filter is simply mounted in place of the intake pipe. Water is drawn in broadly around the dirt trap (filter basket). This is equipped with filter material that can be easily cleaned and replaced. For cleaning, the dirt trap can be easily removed – preferably with plant tongs. It retains coarse dirt right at the intake area and prevents the filter media from becoming clogged too quickly. This significantly extends the biological decomposition process in the external filter and increases its lifespan. The easily detachable (Easy Click) and quickly cleanable filter basket ensures gentle filtration. It consists of two filter containers with filter cartridges and is expandable as needed. Compatible with installation set 1 and all Eheim external filters (except for professional 3e and classic 1500XL).