The Sports Illustrated Swimsuit issue features page after page of beautiful women, almost always a size 4 or under. But this year, for the first time, not one, but two plus-size models are in the magazine. The first, Ashley Graham, isn't really a Sports Illustrated model -- she's a size-16 model donning a black bikini in an ad for Swimsuits for All. 

The second, Robyn Lawley, was in fact chosen for the magazine, and is wearing a size 12 offering from her own line of bathing suits for women with curves. 

So what do the traditional tiny-waisted swimsuit beauties think about these pioneering plus-sizers?

Rookie SI model Erin Heatherton, who we spoke with at a Sports Illustrated Swim City event in New York City promoting the 2015 issue, says the special issue has always displayed women of somewhat different shapes and sizes.

“It’s the number one magazine to promote a healthy body image for women," she told FOX411. " Ultimately, these [plus-sized] women should be seen and embraced.”

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Model Sara Sampaio said models shouldn't be labeled one way or another, and would like to see the label "plus-size" disappear altogether.

“I really don’t think we should label models as 'plus' or 'runway'. Models are people. A lot of people like to make us some species that are not human, we are normal people," she said. “This is a whole production....  It’s not like I wake up like this. There is makeup, there is hair, and there is the perfect light. There is a whole team that gets you to get that perfect picture. It’s a fantasy.”

SI model Samantha Hoopes agreed.

“Being a woman is hard," she said. "Everyone has different body shapes and frames but it’s awesome we’re able to celebrate the beauty of everyone and say ‘Oh, you don't have to be a size zero' because that’s unrealistic.”

BMG Models President Robert Casey told FOX411 casting a plus-size woman in Sports Illustrated “is a very significant move that broadens the perception of what a typical model should be.”

Casey said SI most likely made the decision to feature the curvier models in response to the current trend of body acceptance.

“I think the decision came now in response to the current zeitgeist," he said. "The body acceptance movement has been an increasingly loud voice and SI’s choice echoes this societal shift.”

WATCH: Four4Four: Swimsuit models, news anchors under fire!

Fox News.com Reporter and FOX411 host Diana Falzone covers celebrity news and interviews some of today's top celebrities and newsmakers.  You can follow her on Twitter @dianafalzone.