The IWS copper disc is for use with the IWS systems and prevents unruly roots and potting mix from leaving the pot. Simply place in the bottom of the inner pot prior to potting mix and check periodically for any roots escaping the bottom. The discs are effective right through your grow and only need to be replaced when you are ready for another crop.
Unit 7, KPC Business Centre
TN24 0BP Ashford, kent