PRE-OWNED, VERY CLEAN, VERY CLEAN, WITH TWO VERY TINY INDENTATIONS, EXACTLY PARALLEL TO EACH OTHER ON BOTTOM EDGE (ABOUT 2MM ACROSS AND NOT AT ALL DEEP, SO I AM NOT EVEN SURE IF IT WAS MADE LIKE THIS) :

SIGG,Swiss Water Thermo Flask Hot & Cold ONE, .5 ML (17 OZ).

Made from high-quality 18/8 stainless steel is vacuum-insulated and keeps drinks hot or cold for hours. The innovative ONE cap makes the bottle even more comfortable to use: Carry, open, drink, close and seal – all conveniently with one hand! It allows easy drinking on the train, in the car and in urban life situations - safely locked. This thermo flask keeps your drink 12 hours hot and 20 hours cold.

I HAVE A CLEAN, TOBACCO-FREE HOME.