Remember the Camillus shroud cutter knives? These reminded me of them a bit, so I ordered a pair. I make no claims about durability, but both deploy smartly with push of button and clip onto belt loops or keychains with no drama. Less than 3" in length. 2 for $13. Handy for removing banding or cutting cordage. Not sure how they would do on seat belts.
https://www.amazon.com/ITOKEY-Seatb...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
https://www.amazon.com/ITOKEY-Seatb...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==