Found in arrse:
Like many other soldiers I bought myself a 350ml thermal mug. After making coffee on a recent exercise, I tried to dunk a biscuit fruit from my ration pack and was shocked to find it did not fit into my mug. I snapped the biscuit in two and dunked it sideways. Because it did not have as much length, I could only dunk a little before scolding my fingers. If biscuits were made 6mm smaller, they would fit, which would increase morale. - LCpl, 1(UK) ADSR, name, address supplied.