Two slim-profile mouthguard cases. These cases are sized to fit retainers, night guards, orthodontic retainers, and custom trays for at-home whitening. Size (at the largest points): Width: Approximately 7.5cm Length: Approximately 7cm Height: Approximately 2cm Fits one mouthguard. Brand new, unused, and in excellent condition! ☺︎ The compact size makes them very convenient for everyday carry! They are sturdy cases. These cases were included with the purchase of Opalescence at-home whitening products, but I don't need them, so I'm selling them! They should fit a retainer without any problems. Opalescence