PARIS--From train tickets to couture goods, the French are all about swap sales these days. But how about an entire boutique exchange? Yesterday, Colette tried its first shop swap with London art boutique and communication intelligentsia Kessels Kramer, aka KK Outlet. The concept goes as such: Sarah Lerfel of Colette and Danielle Pender of KK Outlet each hop to the other side of the channel, bringing along a crème de la crème selection for their new audience. (The terms "pop-up" and "swap" seem equally viral these days, so why not combine the two?) Yesterday, on the chic rue Saint-Honoré, KK Outlet revealed hipster art books, limited editions, art works by Erik Kessels, but also collaborative products such as "divided loyalty" scarves, and more.