Acupressure bracelets, the large are less intense than the small or acupressure rings, 

sizing of small or large is about pressure - both will stretch to any wrist size.

The small size are the same, more intense feeling as an acupressure ring.  This would be my recommendation for nail biters, and other self harm control.

I use mine by running it up and down my arm during extreme anxiety, personally i find they help me avoid panic attacks. It is suggested that you run it up and down your arm 20- 40 times to change your focus and disrupt your unwanted behavior.

People sometimes use them for nail biters, skin pickers and hair pullers, to divert the behaviour where possible with this firm pressure.

Not for young children, 8+ 

Use under adult supervision 

Choking hazard