While not strictly flannel base layer bottoms, the Columbia Women's Glacial IV Print 1/2 Zip Fleece Pullover is a top-rated option for layering with your base layer bottoms. This pullover is made from a soft and cozy fleece fabric that provides warmth and comfort. The 1/2 zip design allows for easy ventilation and temperature control. The pullover has a stylish print and a flattering fit that looks great on any body type. Whether you're hitting the slopes or running errands, this fleece pullover will keep you warm and stylish.