Magnets for SmartThings Multipurpose sensors are vayring a lot

I am not sure about ST promoting this usage, i don’t see it on https://shop.smartthings.com/products/samsung-smartthings-multipurpose-sensor.

Now, if your purpose is to know when the dryer is done, i would rather go for a smartplug and monitor the power consumption. That’s what I did for a pump here Sharing my implementation of grey water pumping