The price varies depending on whether you choose 1 or 3 stones. See more tumblestones here
Grey coloured Magnetic Hematine tumblestones. These stones have shiny, metallic gunmetal grey colouring. Kids love these magnetic stones but there's a therapeutic aspect to using more than one. Putting them together & pulling them apart again, similar to using the indentation on a thumb stone, can distract the mind & provide stress relief.
They're also great to use as fridge magnets.
Hematine is a man made stone that looks like Hematite.