It was a neck gaiter made by Lockhart IIRC who also made oil coolers for motorcycles and other vehicles (whatever they are). It attached via hook n loop to the bottom of the helmet and dropped down to the shoulders.
It was effective but a little cumbersome to use as you had to slide it over your head with your helmet or put it on first and try to attach it once the helmet was on. Occasionally movement would pull it off the helmet. It couldn't be stuffed inside a jacket or it'd be ripped off when turning your head. So it did leak some air but that helped reduce the CO2 build up when the visor was down.
(My Bell Star wasn't vented.) So the BUFF idea is really much better.