FR04 FLOW RED 2021 RO Membrane Replacement (Pair) - Compatible with Reverse Osmosis Water Filtration Systems for Clean Drinking Water at Home

These membranes is suitable for FLO, FLOW RED, and FLOW RED+

These are sold in pairs,

There is a 'spacer' in the packing which you do not need to use. 

Note the orientation of the RO-MEMBRANE when you remove it - one end has a rubber o-ring.  Membranes must be installed correctly with the direction of FLOW.