This tumbler is shown on page 52 of Westmoreland Glass Volume 3 1888- 1940 by Lorraine Kovar. Kovar added the "A" to this line number as Westmoreland assigned the number 1909 to two different lines.
This is the 6.5 in. tall Ice Tea Tumbler.
This line appears only in the 1926 catalog and most pieces are conical in shape. It is characterized by the almost horizontal ribs found on all pieces.