Be confident in your purchase we're an Authorized Coral RX Dealer. How cool is that?!?!? Features: Made in the US. Filtration up to 200 microns. Includes a supportive plastic ring. Standard 4-inch or 7-inch sizes fit many filters and tanks (sold separately). Effectively polishes water. A quality filter sock is an integral part of keeping your aquarium water clean, healthy and free of debris. Fitting the Simplicity 7" x 16 " 200 Micron Filter Sock w/ Plastic Ring (Single) on your filter (sold separately) means you know your fishy friends will swim in the cleanest, healthiest water possible. Made in the US from durable material that will last, this aquarium accessory comes in a variety of sizes and styles to fit your tank?s needs.