Nice flask.
Brandes Brothers were August, Frederick and Dederick
Business name timeline:
Brandes Bros. (1880-1885), August Brandes (1890), Brandes Bros. & Co. (1895-1906)
Address timeline:
103 E 42 nd St (grocers: 1880) & 872 11 th St (Liquors: 1880), 319 3 rd Ave (1885) & 119-121 E 42 nd (1885-1906) & 135 E 125 th (1895)
So yours seems to be from the 1880-1885 era.
Don.....