Light Green One Half Gallon Jug with twist cap.
 
Says One Half Gallon on both sides.
 
Says Duraglass on both sides
 
Bottom says 1513-W    20  and what looks like and I in a circle then 54 and 30
 
Approximately 10-1/2" tall.
 
Cap is old an rusty.
 
See pictures.
 
Thanks for looking!