The 41400009 carbon block is compatible with Hydrotech's 1240-Series (E, M and Pro) RO Systems and used as a pre- or post-filter as well in Microline's CTA and TFC RO systems. Use this product to reduce chlorine, taste, odor, and sediment as small as 5 microns. Other compatible RO systems include the HT101, HT102, HT102 and HT123 Series Systems.