White Castle invites customers far and wide to enjoy a complimentary Cheese Slider on National Slider Day, May 15. All they have to do is visit their favorite White Castle and present a digital coupon that can be found on the company’s social media channels. No purchase is necessary to receive the free Cheese Slider.

National Slider Day is one of the most significant days of the year for White Castle. It gives the 101-year-old, family-owned business an opportunity to celebrate the little square burger that made them famous while showing their appreciation to the loyal customers who have fueled White Castle’s popularity and success through the years. White Castle expects to give away tens of thousands of Cheese Sliders at its more than 350 locations.

“Giving our Cravers a complimentary slider on National Slider Day is one way of thanking our devoted fans,” says Jamie Richardson, vice president at White Castle. “We’re so grateful for their unparalleled passion for our sliders as well as our other delicious menu items.”

White Castle offers more than 15 varieties of beef, chicken, fish, egg and plant-based sliders for breakfast, lunch and dinner, including the brand-new 1921 Slider, the Chicken & Waffles Slider, the Panko Breaded Fish Slider, the Breakfast Slider and the Impossible Slider, as well as limited-time seasonal favorites, like the Seafood Crab Cake and Sloppy Joe sliders. There’s literally a slider for every taste, available any time of day.

White Castle fans have been known to go to great lengths, both literally and figuratively, for White Castle sliders. In fact, according to a recent national survey of 2,000 self-professed hamburger fans, nearly half (48%) of them said they would travel 30 miles or more for a White Castle slider, while more than 1 in 4 of them (27%) would go 50 miles or more. Fortunately, no one needs to go that far to satisfy the crave. White Castle’s coast-to-coast retail presence means people can find several of these great-tasting sliders, including The Original Slider and the Classic Cheese Slider, in the freezer aisles of their nearby grocery, club and convenience stores.

Both the retail and restaurant versions of the tasty little burgers can be used to make all types of delicious dishes, from soups and salads to quiches and casseroles. Check out the  White Castle recipe website for inspiration.

White Castle introduced National Slider Day in May 2015 to honor the iconic, steamed-grilled-on-a-bed-of-onions hamburger. Though the Original Slider is highly regarded for its hot and juicy taste, the 100% beef patty is equally as famous for its 2-by-2-inch size, making it so easy to eat it was dubbed the slider.

Here are a few more fun facts about White Castle sliders:

• The founder of White Castle invented the slider in 1921 by smashing a meatball on a griddle with a spatula.
• In 1954, White Castle introduced square sliders to maximize griddle space.
• That same year, White Castle added five holes to the slider patty to increase cooking speed and help the patty absorb the flavor of the grilled onions.
• In 1962, White Castle introduced Cheese Sliders as a standard menu item, more than 40 years after the first slider was served.
• In 2014, Time magazine declared The Original Slider to be “the most influential burger of all time.”
• National Slider Day falls smack dab in the middle of National Hamburger Month, another White Castle creation meant to honor the fast-food hamburger industry it pioneered.