The lower tray of VitalSleep can be adjusted forward. This will advance your lower jaw to open your airway by bringing the back of your tongue forward, unblocking your airway.
Turning a screw clockwise will bring the lower tray forward.
Each screw should be turned equally to not skew the device.
To help the screws engage it may be necessary to squeeze the top and bottom trays together as shown in the image below.