What Our Gearhead(R) Experts Are Saying:"I wear this under a flannel on cool mornings and it never adds bulk, the snug fit just disappears under whatever goes over it. The merino corespun fabric keeps me regulated whether I'm outside or back at my desk by afternoon."The BodyFit 150 Ultralight Anatomica Crew from Icebreaker earns its spot as the layer worn closest to skin on days that shift from cool mornings to warmer afternoons. We reach for it under a flannel or shell when the day starts brisk, and the ultralight merino corespun fabric regulates temperature as the layers come off. The slim, snug fit sits close to the body without any extra bulk, built specifically to work as a foundation piece rather than stand alone.