Clearly, their sibling bond is unbreakable. Presley Gerber just paid tribute to his little sister,
Kaia Gerber, by getting a permanent tattoo of her name on his left arm, just above the elbow on his tricep. The 18-year-old and 16-year-old models were visiting NYC at the time — presumably for New York Fashion Week — and big brother Presley stopped into Bang Bang Tattoos for the new ink. Watch the video above to see Presley's sweet tattoo, along with pics from the special day!

Of course Kaia tagged along for the visit, as did Presley's girlfriend, 19-year-old Charlotte D’Alessio. While neither of the girls received tattoos with Presley, they offered the best moral support during the painful procedure, snapping pics throughout.

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Just below Kaia's name written in a pretty script, Presley also chose to get the Roman numerals XXIII tattooed. People aren't sure of the meaning quite yet, but some speculate it corresponds to the siblings' birthdays since Presley's birthday falls on the second of July while Kaia was born on the third of September.

Others, on the other hand, think it's representative of the date Kaia made her couture show debut —she first walked the Chanel runway during Paris Fashion Week back on Jan. 23, 2018. Some even thought it could be a combination of both theories. Regardless of the meaning, it's safe to say it's somehow in honor of his little sister!

presley gerber, kaia gerber, cindy crawford, rande gerber getty

Luckily for Presley, both mom and dad were OK with the permanent tribute! Cindy Crawford and Rande Gerber both took to Instagram to post a comment on their son's Thursday, Feb. 15 photo. "Cool," the 51-year-old supermodel wrote, while the proud father gave his stamp of approval with a "RG + JG APPROVED!" comment. And of course Kaia loved the tattoo: "@presleygerber best big bro ever," she wrote.

Presley recently gushed about his close family, and it's so nice hearing how much they love and support each other. "We literally drove from our house to work together, then drove home together. But we’re a really tight family, so it was just like going to work with one of your friends. It was so fun, and easy," he revealed to People when asked about his Super Bowl Pepsi ad he worked on with his mom. So sweet!