Foam gets where liquid can't.
Why it works when
nothing else has.
Every basin has a small overflow hole near the rim. It drains into the same pipe as everything else, it never dries out, and no brush or sponge can reach inside it.
Liquid cleaners run straight down and out in seconds. The foam swells to fill the pipe and holds against the wall, so it stays in contact with the buildup long enough to break it down.
Breaks down the three things that actually narrow a household pipe, so a slow drain runs properly again without a plunger or a snake.
Non-corrosive on PVC and metal pipes, so it works as regular maintenance rather than an emergency-only product you keep under the sink for years.
Pressure forces the foam back up through the overflow — the one part of your sink that has never been cleaned, and usually the real source of the smell.
The greasy film coating the pipe wall is what catches the next piece of hair. Strip that film and blockages stop returning as quickly.
Shake, press it into the drain, walk away for half an hour, rinse. No scrubbing, no mess in the basin, no waiting in for a plumber.