This sweatshirt is a 50/50 Polyester/Cotton mix.  They offer real protection for your inmates in the winter (that's the whole year round in the UK - just a joke about the weather here).  If they go over the wall then the helicopter will not have a problem spotting them!  Medium measures 22 inches (56 cms) shoulder to shoulder and 24 inches shoulder to hem.  They have elasticated hems and cuffs.