Pro4+ filter replaces the EHEIM Pro 3 range.This new filter doesn�t just boast a new sleek black color but it also has a Range Xtender Function which serves a few purposes. These filters can handle aquariums between 30-160 US gallons (Depending on model purchased).†The square design of this filter ensures that high stability and increases your filter volume compared to rounder filters.1. Extends intervals between cleaning by using a bypass and skipping right over the fine filter pad. 2. You can hook up a pre-filter (4004320, sold separately) in order to clean up quickly after disturbing your gravel or doing big clean up, without putting a large load on your filter (sucks up large debris before going into the Pro 4+). 3. You can hook up a pre-filter (4004320 equipped with a carbon pad, sold separately) in order to remove toxinsfrom your aquarium. As with most EHEIM filters, the Pro4+ comes complete with filter pads and media and all installation equipment. Also has a primingsystem and secure hose adapter.