Standard wide mouth Nature 2 replacement filter cartridge.
Has a open top and the bottom has a coarse thread spigot.
The open top is designed so you can purchase a cap that will hold a Nature 2 stick in the centre of the filter.
Filter dimensions: Height- 225mm(not including spigot), Width- 143mm, Spigot ID- 35mm.
Commonly used on Signature Spas, Spa-Quip and Others.
Also available in Microban®