Magnetic Hydrometer Holder

I recently acquired these hydrometers:

https://www.amazon.com/dp/B08P3QJJZL?psc=1&ref=ppx_yo2ov_dt_b_product_details

These holders have 3 6mm magnet holes (because Gridfinity) such that you can put them anywhere. the inverted one is probably unnecessary for the overwhelming majority of uses, but it allows for the hydrometer to attach to the back of something and hang down.