Why am I considering buying a flask? I don't need one
I think you should get a 500ml flask in case you need it,
I hear both thermos and Zojirushi are good https://www.amazon.co.uk/gp/product/B01BTX232Y/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 and https://www.amazon.co.uk/Thermos-Ul...ywords=thermos+ultimate&qid=1579434091&sr=8-2