The pair who are brother and sister, have been working together since the beginning of their careers, with Finneas producing all three of the singer's albums, including her 2019 debut, 'When We Fall Asleep, Where Do We Go?', and 'Happier Than Ever' in 2021.
He also produced Eilish's latest album, 'Hit Me Hard And Soft'.
But in a recent interview, Finneas has explained who she has given Eilish a "basic" kit to help her produce music by herself.
“I’ve been setting up Billie’s recording studio for her so she can do home production without me, because she’s very good at it!”, Finneas said.
He added: “And it’s funny, I’ve been giving her, like, the bare minimum of stuff, just so that she learns it all. I’m like, ‘Listen, I could give you all the stuff that I use now, but it took me years to even have a use for it. And, if I give you this basic thing, it’ll make sense to you right away".