These filter heads will require the following fittings:
3M Filters
702521 - 3/8" Male (BSPT)
702522 - 3/8" Push-Fit (DM-Fit/John Guest)
800141 - 1/4" Push-Fit (DM-Fit/John Guest)
Brita
8001110 - 3/8" Female (BSPT)
800110/P - 3/8" Push-Fit (DM-Fit/John Guest)
800111 - 3/4" Female (BSPT)
800111/P - 3/8" Push-Fit (DM-Fit/John Guest)
800116 - 3/8" Female (BSPT)
800116/P - 3/4" Push-Fit (DM-Fit/John Guest)
BWT
800178 - 3/8" Female (BSPT)
Everpure
800130 - 3/8" Female (BSPT) (comes as standard, also available in 3/8")
800130/P - Push-Fit (DM-Fit/John Guest)
iX
800159 - 3/8" Push-Fit (DM-Fit/John Guest)