To celebrate 100 years of serving tasty burgers, White Castle gave customers a treat from its past with the new 1921 Slider. Per a company statement, the 1921 Slider goes back to the original concept where a meatball was pressed flat in order to make a hamburger patty.

While other brands have adapted that smashed burger on the grill concept, White Castle made the original. The menu item has been available as a limited release offering, but its popularity has pushed the chain to add it to the permanent menu in all of its locations.

Looking specifically at the new menu item, the 1921 Slider seems to be a little thicker than the traditional famous White Castle sliders. Served with grilled caramelized onions, tomato, cheddar cheese, pickles, and lettuce, it appears to be a meatier bite.