A built-in fridge with a sliding door is attached to the front panel of your fridge via a door guide. Because the fridge and front panel both have their own hinge, the door slides open and shut via the door guide while the fridge door slides along with the panel. Contrary to a built-in fridge with a door-on-door system, there's a gap between your fridge door and cabinet door. If you purchase a built-in fridge with a sliding door system, it's important to pay close attention to the niche dimensions of your fridge. This way, you're certain that your new fridge will fit. If you're currently using a fridge with a door-on-door system, you can't switch to a fridge with a sliding door system.