Quick take
RKIN recommends replacing the hydrogen module every 6–12 months as needed. The current replacement collection lists it around $54.70.
What RC-HGPEM is
The PEM module is a U1-specific hydrogen component, not the RO membrane or alkaline post-filter.
Replacement interval
RKIN currently publishes a 6–12 month replacement schedule.
Current price
The current U1 replacement collection lists the hydrogen module at about $54.70.
Bundle economics
U1 owners should compare individual cartridge prices with RKIN’s one-year and two-year filter bundles before buying each consumable separately.