This is a genuine flight crew life vest removed from a line aircraft.  We have a bunch.  Just out of curiosity, we had a contest among ourselves, to see who could open it, put it on correctly and be ready to jump into an ocean if we had one.  NOBODY could open it by hand.  It is a nylon bag sewn with nylon thread.  It cannot be done without a tool.  We strongly suggest all life vests on a plane come with a Stanley knife, better known as a box cutter.  That way, after finding the vest, finding the knife, cutting the bag without puncturing the vest or severing an artery, you are ready to go swimming.  That should only take about 6-7 minutes.  (Note; planes float for an average time of 2-3 minutes).
 
Now do you still wonder why the 737 Max is a piece of crap?  Same engineers.