Red Starfish Filter Sock Holders are an inexpensive, easy and effective way to convert a regular aquarium into a sump. Simply hang the Filter Sock Holder on the side of the sump then secure with the adjustment screw. The Filter Sock Holder accommodates aquariums with a trim of up to 1” and fits most standard-sized 4" filter socks. Made of high-quality acrylic. One 4" Mesh Filter Sock is included