Black Tourmaline is so great for blocking negative energy and it also blocks radiation from your computer, phone and wireless components when you wear it on your wrist(s). Strung on two strong elastic threads. Easy to pop on and off if you just want to wear them at the computer on days that they don't really go with your outfit. Some measure slightly larger than others (8") and sit more like a bangle bracelet.
If you were to wear jewelry to bed, this would be a good choice as Tourmaline enhances sleep.