I'm not sure what this is but I know it's connected to my carb , I'll upload photos below , just got a new carb and a rebuild , over paid too much for a rebuild and I just noticed after 2 weeks of getting my car back a part connected to the card won't stay on . Please inform me of what part this is and how important this is for me to use while I'm driving . Thank you in advance

 

Vacuum diaphragm for cruise control

 

which means you can totally do w/o it
some cars used to not even have cruise control
hard to believe but true

 

Thanks guys