It's important to have a few critical transitional through-pieces in your wardrobe. These pieces, once you find the right ones, will save you time, money, and space in your wardrobe. Having the right thing for the right thing centralizes your thinking and makes getting dressed fun and less of a chore because you can be confident knowing that you have something that's not only appropriate but looks and feels good.
This kind of outerwear is most suited for, but not limited to, the changing of the seasons, i.e. we are talking about winter through spring and fall, mostly. These are pieces that can tie your whole wardrobe together.
They don’t make them like they used to, I would go so far as to say that it's even easier to find these pieces vintage than new. There's so many classic silhouettes to choose from. 
Ode to the trench:
love you Jane
