Filbur FC 3129 Micro Klean Filter Cartridge w Hose Adapter zodiacjandylaars A spring like this is A spring like this is useful because it helps the bypass mechanism move and respond the way the heater was designed to operate The TC440 MB fit gives this assembly practical value because standpipe components work best when they match the original internal layout closely The Micro Klean design and included hose adapter format give this cartridge practical value because filtration components work best when the replacement matches the intended housing and connection arrangement That keeps routine service focused and efficient