Simplicity 7″ Filter Sock Holder – BlackGreat solution when using a glass aquarium as a sump.Compatible with most brands of filter socks.Available in 4-inch and 7-inch sizes.Perfect, inexpensive option for use with do-it-yourself sumps.Backed by Simplicitys renowned customer support.Easily keep your filter sock in place with the Simplicity Filter Sock Holder. This important accessory is durable and perfectly fitted to ensure it stays in place while keeping your tanks water healthy and clean. The black filter sock holder fits sump (sold separately) edge thicknesses up to 1.75 inches and works with most brands of filter socks (sold separately).