Been awhile since I skydived, but it appears what USED to be called an ADD (automatic deployment device) now according to USAPA is an AAD.
Or I’m old and scrambled up the acronyms.
Automatic deployment device or Automatic activation device. They will deploy your reserve ‘chute if you pass a set altitude at a velocity greater than a set speed.
No way I would go out the door without one, I thought for sure by now everyone had them. They were only $250 in 1997, cheap insurance.