Hypoinjector wristband

A hypoinjector wristband was a nondescript wristband that was designed to protect the wearer against poisons and other environmental toxins.

It had room for 8 doses of vaccines, antitoxins, or other medication. An onboard sensor would constantly scan the wearer and if it detected the presence of something deadly, it would automatically inject the appropriate chemical to counteract it. It operated on 2 energy cells that allowed 5 days of constant use.