I need some of this part but I’m struggling to find any sets they came in:
BrickLink calls it Technic, Pin Connector Toggle Joint Smooth Double with Axle and Pin Holes.
It comes in a number of sets listed here.
Here is some detail of the sets containing the part listed in order of year released (newest first). The green highlighted sets are currently still available on Lego Shop.com (US) at the time of this answer:
Since most sets didn't/don't come with very many of this piece, you're best bet is probably sourcing them from Bricklink or somewhere similar. They're about .20 cents (USD) or less on Bricklink.
They are also available for purchase individually at Lego Shop.com for .42 cents (USD):
I think a list of links might be more-useful than an image. Good point on the buying advice though! Aug 10, 2019 at 18:00
1Because I don't know the age, language comprehension, or experience level of the people asking the questions, I try to focus on clarity. Links are absolutely useful, but also susceptible to breaking. I try to present an answer that can stand on it's own if the link(s) fail. I also feel that posting a line or two of just links is lazy and not much better than "one line" answers. I am still new here and would appreciate any constructive criticism from veterans such as yourself. I am interested in contributing here without "stepping on toes".– JohnnyBAug 10, 2019 at 19:11