I don't see it online but in store I bought a one litre stainless steel flask from Tesco last week for Â£3-95. I can remember when these things were expensive. Admittedly the only flask which will survive really rough treatment is the big heavy Stanley jobs, which are a pain in the arse weight-wise when they are empty. The Tesco flask has a neck wide enough to take those little tinned spuds - drain fluid from spuds (and/or kidney beans, chick peas etc), chuck them in the flask, add boiling water and stopper, heat soup in the saucepan, carefully drain off boiling water from flask leaving hot spuds and pour in the soup. Admittedly all the fluid has to come out to get the spuds out. There also seems to be quite a lot of heat coming through the stopper. It kept boiling water scalding over ten hours, though, so quite usable for Â£3-95.