H2O Economy 3+ replacement membrane G50/L90 (50 GPD) = ROWA 1812-50 GPD complete with housing.
This membrane replaces TFC 24 if necessary, requires flow restrictor 250 ml (make from 2007)

Important maintenance note:
The manufacturer recommends replacing the flow limiter at the same time as changing the membrane.

Alternatively, the function of the flow limiter can be checked before and after changing the membrane:
How to check function (wastewater flow test):
Shut off the cold water supply. Shut off the tank. Open the tap on your sink. Pull the red hose leading from the membrane chamber into the white flow restrictor (labeled "150"* or "250 ml") and from there into the black permeate pump. Detach it from the pump exactly there (hold back the clamp ring + pull firmly) and hang it in a measuring container. Now turn the cold water back on. During normal operation at 4 bar, approximately 250 ml (*: or 150 ml) of rinse water should be produced. If significantly less or no rinse water is produced, the flow restrictor must be replaced immediately. Any membrane would be destroyed within a short time during operation.
By the way: A perfect membrane delivers about 50 to 100 ml of pure water per minute (measured at the tap).