When it's cold or wet I wear one of these, 1st one lasted me 6 seasons, digging, lamping, on the hills, when you get warm unzip the sides, little elasticated strap you can clip under from front to back stop it riding up, got matching trousers that I use for fishing, never been cold or wet, my mates in armed forces swear by them. Been up in the Highlands - 10 plus, warm as toast?base and midlayers paramo and mammut.