What kind of shoe is a "number"?

The sentence reads as this "At Giles’ brilliantly quirky spring show, skinny low-slung kitten heels by Christian Louboutin stalked the catwalk; there were crocheted, beribboned kitten-heel numbers at Missoni and black and gold kitten-heel sandals at Marni and Givenchy". So I suppose "numbers" means some kind of shoe here. Is it something like sandals?