Well, Snap On, as I understand the situation, bought out the old Vacuum Grip company many decades ago, which is how their plier line came about! Those were top grade pliers, and no less so for Snap On's takeover! Indeed, some of the original 'Vacuum Grip' models were still offered up till the late 80's - I bought some!
Back then, those all steel Vacuum Grip models were really the top end of their line...