The US Navy Expeditionary Medal was authorised for issue in 1936. It is awarded to service personnel who have landed on foreign soil and engaged in operations or served against armed opposition to which no service or campaign medal exists. The US marine corp issued a similar medal (authorised 1929). Awarded for such operations as Wake island in WW2 where a clasp was added to the medal. The invasion of Grenada 1983, Lebanon, Libya and the Persian Gulf would also qualify for this award.
Left: George Studley Issue circa post 1936, made by Davidson, Middle: Volupte Inc, NY late 1950 to 1969 issue, Right: Modern 80’s issue, marked “W GI” possibly for Waterburybutton Co, Cheshire, Connecticut.
All 3 have a nice striking but vary in thickness with the Volupte issue being the thickest.
Other makers were: US Mint and His Lordship Products.

Obverse.

Reverse.
The George Studley issued medal is mounted on a ring suspender and has a full wrap brooch whereas the Volupte and W GI are knob suspension both of which are slightly different and are crimp brooch.