EVER since it appeared on Style.com earlier this year, the Slash, a lambskin shoulder bag from the New York accessories label Boyy, has been a hot ticket. Stores have reordered. There’s buzz on the blogs. The fashion muse Lou Doillon has become a fan. Along with Alexander Wang’s Donna and Brenda, Jerome Dreyfuss’s Billy and Proenza Schouler’s PS1, it has become, among a set of understated fashionable women, the bag to own this season. Apparently “It” bags aren’t dead; they’ve just gotten cooler.

“It’s not about the big names anymore,” said Kris Kim of La Garçonne, a shopping site that sells (and sells out) of many of these bags. “It’s more under-the-radar now. You have to look for it.”

Up next: the Alexander Wang studded Coco bag from his fall collection. Ms. Kim already has a wait list for it.

Boyy Slash shoulder bag, $595 at boyybag.com.