It&rsquos an iconic fixture of comfort and hospitality right across the high Himalaya. I&rsquove drunk endless cups of hot water and salted tea from these sturdy flasks everywhere from western Ladakh to eastern Arunachal. The brands are Chinese but I always see them as a reassuring marker of the resilience of Tibet&rsquos material culture. And I&rsquove often been tempted to take one home &mdash but always resisted because they are almost too ubiquitous.