an upper tray with a first upper section, a second upper section, a first upper inner wall, a second upper inner wall, an upper outer wall;

an anterior bridge connecting the first upper section to the second upper section, creating an open section between the first upper section and the second upper section;

a lower tray separate from the upper tray, with a first lower section, a second lower section, a first lower inner wall, a second lower inner wall, a first lower outer wall, a second lower outer wall;

a lower bridge connecting the first lower section to the second lower section;

a first upper post located the first upper section;

a second upper post located on the second upper section;

a first lower post located on the first lower section;

a second lower post located on the second lower section;

a first side strap removably connecting the first upper post to the first lower post;

a second side strap removably connecting the second upper post to the second lower post, the first and second side straps a paired set identical in length to one another, in which mandibular advancement is variable by swapping the paired set of first and second side straps for a different length paired set of first and second straps, the different length strap pairs further enabling the anterior bridge and lower bridge to be spaced apart from a user's anterior maxillary teeth, anterior mandibular teeth, and adjacent anterior gum tissue when the oral appliance is positioned in a user's mouth;

a thermal impression material on a surface that faces dorsal dental surfaces of each of the first upper section, the second upper section, the first lower section, the second lower section; and

in which the first lower section and second lower section each include a lingual surface designed to engage a user's tongue.