It filters your shower water depending on the type you get, in my case it's a simple chlorine filter from Brita. All the ones you see online are largely the sam

It filters your shower water depending on the type you get, in my case it's a simple chlorine filter from Brita. All the ones you see online are largely the same type with different branding. It's not to expensive, personally I value my health and I've lived in shitty conditions with really bad water. Water flow can change depending on the outlet type you get, similar to a hose. Reduction of flow doesn't really happen unless you get those white-label transparent with colorful rocks type filter attachment, I've heard bad reviews of those.