new in bag, AERO overshoes
these are from the team GB overstock - from the olympic / paralympic teams and the development teams - likely all the same issue i think. 
I'm pretty sure they'll have gone with the SKY kit  (them having sponsored the development teams but not the actual competing teams)





Approximate OverShoe measurements - measured externally and flat along from back of heel to end of toe (note that your shoes go internally the overshoe and are not flat - please factor that in )labelled sizes often show no real standardisation - often running large or small for given labelled sizes.
use my measurements above and beyond the given labelled size to ensure you get the actual size you want

S 23.5cm
M 24.5cm
L 26.0cm
XL 26.5cm
XXL 27.5cm
3XL 28.5cm