In what may be the chicest example of “You scratch my back and I’ll scratch yours,” a pair of French labels are teaming up for a two-way collaboration this spring. Swim and lingerie house Eres has designed Longchamp’s first bikini, and, in exchange, the venerable leather goods house known for its handsome luggage and handbags has loaned its popular Le Pliage silhouette to Eres’s new beach tote. The swimsuit ($382) is adorned in a fanciful rose-petal print (in fuchsia or yellow), and the nylon and patent-leather bag ($230) comes in navy or white. “Eres and Longchamp share the French know-how,” says Sophie Delafontaine, Longchamp’s artistic director. Fitting, since her company began making bags in 1948, while Eres got into the swim biz two decades later. Or put another way, it’s about time (longchamp.com, eresparis.com).