I've been watching a ton of Marcs videos on Youtube before signing up for ArtSchool, and there's this one brush I always see him using for shading. It's kind of this upside down triangle looking shape.
He's using it at this current timestamp (4:45);
What brush is it?
Is it one from this pack? https://cubebrush.co/mb?product_id=p8ynjq
Cheers 
