While Barber Osgerby has collaborated with many furniture companies—including Vitra, B&B Italia, Isokon, Cappellini, and Established & Sons, among others—the line with Knoll was among its first forays into designing upholstered pieces. "Upholstery, for us, is actually one of the most difficult things to do because we’re really into the micro details," Barber says. "Upholstery doesn’t really work like that. It’s a different skill set. It’s about stitching. It’s about where the fabric lies. It’s about the angle of the seat and how soft it needs to be at the front of the seat compared the back of the seat. It’s a whole new set of rules. The seat of a wooden chair is the same in the front as it is in the back. You’ve just got to pick the angle. Upholstery is much more complex."