Only Left (blue) HF4 are available now. HF4 filters have now been replaced by Quickguard
Quickguard filters are that same size as the HF4 filters but only come in white, rather than red and blue.
Quickguard filter come in packs of 8 and cost $15 each (rather than a pack of 16 which cost $30).
These Wax Filters protect your hearing aid receiver from the effects of ear wax.
They should be changed monthly along with your receiver wax guards.