Reality TV star Kim Kardashian bought bottom workout machines for her sisters and her mother.

The "Keeping Up with the Kardashians" star purchased the machines for her family -- including her siblings, Kourtney, Khloe, Kendall and Kylie and her mother Kris Jenner -- which promise to "deliver fast, convenient, b*** -blasting results", reports femalefirst.co.uk.

Taking to her Instagram stories, Kim said: "I got my sisters and my mom a Christmas present but I got myself one too. I'm working out right now and I'm gonna open this and show you guys what I got them. I hope my sisters and mom will like this!" Kim also showed her personal trainer Melissa Alcantara giving it a go.

She added: "Melissa's testing it out. It's the DB method and this is what I got my sisters, all my sisters and my mom, for one of their Christmas presents. God I feel it in my butt a lot. They're getting them today."

Kris has already received her one, taking to social media to share her excitement at opening the gift just a few days ahead of Christmas.

Sharing a video of the machine and sharing her own reaction to the brand new fitness gift, she said: "Kim, what in the world is in this huge box you just sent me? This box is as big as I am. Oh my gosh. Whoa Kim, this is so incredibly crazy. Is this a booty machine?"