Silver Antiques Online has dated this piece to the 1920s.
The body of the flask has a slight curve so as to fit neatly and comfortably into a pocket.

Fully hallmarked at Sheffield in 1921, the flask is an ideal pocket size, is watertight and ready to use and would make a wonderful present for someone who likes a 'tipple' on the move !
Condition ***********************

Used / Good
There are no repairs, however, there are one or two small dinks and some surface scratching as would be expected on a flask of this age.
Fully Hallmarked English Sterling Silver
Dimensions ***********************
Length - 4.5" / Width - 3.0" / Depth - 1.0"
Length - 114mm / Width - 75mm / Depth - 25mm
Weight - 111gm
Capacity - 100mls
Silver Antiques Online has dated this piece to the 1920s.
Specialising in antique english sterling silver.
You can view the stock and full dealer information on the Silver Antiques Online Profile Page