It's not a regular German canteen (Feldflasche) but a "Labeflasche 31".
Produced in numerous variations from 1931 till ca. 1943.
Introduced for medics, but also used with mountain troopers, paratroopers and civil organizations like the Red Cross.
See: https://www.nachrichtentruppe.de/9-alle-kategorien/ausruestung/48-labeflasche-31
poor condition (cut straps). value over here nothing more than $25