On the runway, models wear everything from string bikinis to over-the-top couture gowns. But off duty--most rely on a simple uniform of jeans, t-shirts and, of course, leather jacket. The world's most photographed models--including Kendall Jenner, Gigi Hadid, Rosie Huntington-Whiteley--can't wear just any leather jacket, though, so they rely on Nour Hammour, the French brand that makes custom, personalized pieces.

The brand is the brainchild of Nour Hammour and Erin Conry Webb, who met as students at Istituto Marangoni in Paris. Both were already leather jacket obsessives, and Hammour was working on customizing pre-purchased motorcycle jackets on the side. The Paris-based duo launched the brand, which is named after Hammour, in 2013 with six customizable jacket styles. And it took off from there. Here, Hammour and Conry Webb open up about their favorite celebrity clients, why a leather jacket is a wardrobe essential, and more.

Where did your love of leather jackets come from?

Nour: They have always been a staple in my closet because they make any outfit look cool. Before Nour Hammour, I would buy vintage leather jackets and hand stud them for myself and for my friends.

Erin: I fell for my first leather jacket when I was 17, in a small shop next to Piazza di Santa Croce in Florence – it was a motard style. Leather jackets are a soulmate piece that become a natural extension of yourself the more you wear it.

Who are your favorite celebrity clients?

Nour: Will.I.Am was so cool. It was our first celebrity dressing experience in the first few weeks that we launched. It took us two full days to create his jacket, which was entirely covered in studs. I must have watched his performance wearing the jacket about a thousand times!

Erin: Sarah Jessica Parker-–apart from her impeccable style, she is also the most gracious client. I was also really excited to meet Eva Chen! When she came to our showroom, she spent time learning about the brand and offering advice. Their kindness stands out and is something we are not soon to forget.

Who would you most like to dress and why?

Nour: Beyoncé! Because, Beyoncé!

Erin: Erin Wasson. She is so dichotomic in her style - utilitarian and glamorous at the same time.

Courtesy of the brand.

Define your style in three words:

Nour: Clean. Downtown. Effortless

Erin: Californian. Parisienne. Evolving.

What’s your daily uniform:

Nour: Girlfrnd denim boyfriend jeans, t-shirts and comfy knits. I also live in our Erin jacket.

Erin: Our cropped black Avalon jacket, black high waist COS jeans, ACNE Jenson ankle Boots and a t-shirt.

Greatest hits:

Nour: My grandmother gave me a transparent Chanel bag from the '80s.

Erin: Stella McCartney Smoking Blazer. Three Graces London nightgown. Converse. A 1930s Art Deco mechanical Suisse watch that I found it in this tiny vintage watch boutique in Rome. Diamond stud earrings.

Preferred footwear:

Nour: I’m a sneakerhead!

Erin: Ankle boots – high heeled, chelsea, studded, leopard, anything.

Finishing touches:

Nour: Maria Tash earrings and a perfect manicure

Erin: "Au Bord de la Rivière” perfume by Héloïse de V.

Nighttime look:

Nour: High heels and red cream lip-stain by Sephora – I’ve worn it for 8 years.

Erin: All black and a moto jacket!

Best recent discovery:

Nour: SUBLIME Optical Illuminating Moisturizer by Algenist and Miami Beet Nailpolish by OPI.

Erin: “Lumière! L’aventure commence.” It’s a documentary of 108 films by the Lumière Brothers, sublimely narrated by Thierry Frémaux. Evening adult classical ballet classes at Institut International de Dance Janine Stanlowa.

Favorite stores:

Nour: Plum in Beirut--they have the most beautiful selection of clothing.

Erin: Les Images de Marc Lefebvre in Paris has a wonderfully eclectic collection of Vintage Posters. Galerie Pablo Parra for mid-century French-modernist furniture.

Style pet peeve:

Nour: Anyone who wears flip flops not on the beach or pool.

Erin: Fur-lined Loafers.

Style icons:

Nour: Kate Moss and my grandmother.

Erin: Gelsey Kirkland shaped my style when I was growing up.

Last purchase:

Nour: Saint Laurent Candy heels in all glitter! I haven’t worn them yet but I love looking at them!

Erin: A monthly donation to Planned Parenthood and an Osman Fox Fur Gilet.

Lusting after:

Nour: A painting by Syrian artist Safwan Dahloul.

Erin: Summer picnics in Tuilleries with my American family. And the Yves Saint Laurent Disco FW17 boots.

Favorite haunts:

Nour: Ristorante Napoletano in Paris for the white truffle pizza!

Erin: Au Rocher de Cancale, rue Montorgueil, Paris. El Rio in The Mission, San Francisco.

What's always in your bag:

Nour: My NOOK.

Erin: Kindle Paperwhite, Aukey portable phone battery, Homeplasmine for my lips, Deborah Lippmann Hard Rock Polish .

Favorite places to shop in Paris:

Nour: 55 Croisette.

Erin: Le Bon Marche and 55 Croissette for clothing and La Pharmacie de la Place République for skincare...it’s dangerous.

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