Technical Fabrics Under A Blazer

Manastash Mazama Tri-Blend Fleece Jacket
Buy It Now at Hickorees, $236

Ian Velardi Sportcoat
Buy It Now at Park & Bond, $548

You already rock a down vest over your blazer sometimes (and if not, it's a good look), so why not throw an unstructured sportcoat over a fleece jacket or other technical shell? It'll add that extra padding for the winter and you won't need a bulky overcoat.