Multi-cookers can do so many things: pressure cook, slow cook, make yogurt. (Has anyone actually made yogurt with the yogurt setting on those things?) In any case: they can’t, usually, air fry. But there are replacement lids you can buy to add that feature, without springing for a whole new gadget.
Air fryers don’t actually fry, in the sense that you’re not submerging anything in oil. Instead, they work by creating a heating element on top of the food, like a broiler, but circulating heat rapidly with a fan. It’s a way to create a super-high temperature that’s evenly distributed around your food, just like deep-frying.
If air frying sounds an awful lot like convection to you, you wouldn’t be totally wrong. Both convection—a feature found in many new toaster and full-size ovens—and air fryers use circulating fans to heat more evenly. But air fryers tend to have their fans located above the food, close to it. Convection ovens sometimes place their fans in the back. That makes air fryers capable of delivering stronger heat to a smaller amount of food.
Just like the multi-cookers they pair with, air fryer lids offer several different functions beyond just air frying. These lids can also roast, dehydrate and broil, all of which are functions a regular multi-cooker can’t really handle.