What's this (slide?) gear called?

Hi,

Looking at 'boom boom' - Anders does a good tutorial on it.

any idea what the young lady guitarist playing it here:

【Rei】PLAYS... John Lee Hooker / BOOM BOOM - YouTube

is using on the little finger on her fretting hand? - looks like some sort of slide which can flex at the knuckle.

I tried google searches under 'type of slide' & 'flexible slides' but dont see it , so maybe it's named something else?

Thanks in advance,

Mike

Looks like a solid colored glass slide with an opening at the knuckle. I've never seen one like that but even when I zoom in close it doesn't appear to bend while she's playing. Whatever it is, she's definitely using it to channel Hooker!

Thanks  Aliasmaximus for that, maybe its a bespoke item.