Just good jeans! Kourtney Kardashian flashes flat stomach in ripped denim from Khloe's new line while out with Mason and a bodyguard

By Iona Kirby For Dailymail.com

Published: 20:49 EST, 18 October 2016 | Updated: 04:18 EST, 19 October 2016

Khloe Kardashian has been busy plugging her new denim line Good American.

And her big sister Kourtney showed her support on Tuesday when she stepped out with son Mason and a bodyguard in a pair of jeans from the just-released collection.

The 37-year-old, who was spotted in Calabasas, California, certainly made a great advert for it while showing some skin in black skinny jeans with large rips down each leg.

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Sister support: Kourtney Kardashian wore a pair of jeans from sister Khloe's denim line on Tuesday

Kourtney displayed her flat stomach and much of her slender legs in the denim, which she teamed with a long-sleeved and high-necked black jacket.

The reality star also sported simple black pumps and carried a matching handbag, while looking picture perfect with natural make-up.

Kourtney had earlier been showing fans her hairstyle on Snapchat, which consisted of a bun with braided detail at the back.

She also used the social media app to let everyone know that she was clad in a pair of Khloe's jeans. 

Let it rip: The reality star showed off her legs and stomach in ripped black skinny jeans from the Good American collection

Extra protection: Kourtney was seen taking Mason to an art class while joined by a bodyguard

Beefing up her security: The 37-year-old is being extra careful after sister Kim's armed robbery

The mother-of-three was spotted taking her eldest son Mason, six, to art class.

Not seen were her two other children with ex-partner Scott Disick, four-year-old daughter Penelope and son Reign, who turns two in December.

Kourtney also had a burly bodyguard by her side, having beefed up security in the wake of her sister Kim's armed robbery in Paris last month.

In fine form: Kourtney looked great in the jeans, which she teamed with a high-necked jacket and pumps

Mixing it up: The Keeping Up With The Kardashians star also wore a braided bun hairstyle and picture perfect make-up

The Kardashian family have all rallied around the 35-year-old, who is taking some time off following the terrifying ordeal.

On Monday, Kim's assistant Stephanie Shepherd announced the star's friends and family will be updating her subscription based app and website kimkardashianwest.com while Kim recovers.

Kim is also planning a low-key celebration for her 36th birthday on Friday, with just her family by her side, according to E! Online.  

Plait's nice: Kourtney showed off the bun with braids at the back on her Snapchat

Check it out: Kourtney made sure everyone knew where her new jeans had come from