The lid/cap on the German flask model 1931 (and the like) aluminum.
Gorgeous copy, which is difficult to distinguish from the original, especially if stamped. The lid is without stamps. The lid is completed with a rubber gasket. The peg is not installed in the lid, but attached to it. It needs to be riveted after installing the cap on the flask strap.
Price per set: cover + red rubber gasket + peg (rivet).
How to install the peg in the cover?
The pegs were installed into the bakelite caps with 1 mm margin, and were fixed by a blow. From the blow, the peg expanded and fixed itself. At home, you can fix the peg with epoxy resin (epoxy glue) — this is reliable, safe method and it will give 100% tightness to the cap.
Caps from our "Replika" shop, pegs are inserted but not fastened. All pegs has the same sizes of the top half but different tip lenght.
Original aluminium cap with installed peg. Picture from www.ebay.ca, seller skit1941.