I see Hall effect switches mentioned more in US sites than UK. I'm not sure why you would use these rather than the Chinese-sourced proximity switches, unless you are in an environment where there is a lot of metal around and powerful magnet operation is desirable to avoid false triggering. For example, the proximity switches run natively on 24V. Is it really that there is a strong "not from China" feeling in the US rather than any pure technical reason? Just curious - I've a box of proximity switches in the workshop that I am using, so I've already made my design decision