What is "sip-and-puff"

Sip-and-Puff or Sip 'n' Puff (SNP) is assistive technology used to send signals to a device using air pressure by "sipping" (inhaling) or "puffing" (exhaling) on a straw, tube or "wand." It is primarily used by people who do not have the use of their hands. It is commonly used to control a motorized wheelchair by quadriplegics with very high injury to their spinal cord or people with ALS.