Ever see a space blanket? Otherwise known as A Thermal Blanket, essentially an emergency sheet resembling tin foil in fabric form. Its origins go back to NASA and are based on reflecting the body’s heat, thus retaining warmth.

Columbia’s Omni Heat fabric is like that. Reflective silver circles line the inside of their fleece, synthetic, down, and outwear layers. Take the Powerfly Jacket ($220, 13.6 ounces). The outer shell is ripstop nylon, it has narrow baffles filled with 800 down, and is lined with Omni Heat. It comes with a stuff sack; compressed inside its slightly larger than a softball.

I wore the Powerfly while in my sleeping bag during a cold night recently in Hueco Tanks, Texas. Shortly after putting the jacket on over my T-shirt, I could feel the heat radiate off the Omni Heat. Another time, I layered with it while climbing north-facing tower routes in the Fisher Towers (in winter). The Powerfly was one of about five layers I had to wear to keep warm. I liked the low bulk/high warmth ratio; this meant I could endure multi-hour belay sessions without feeling like the Michelin Man. I took it sport climbing last week in Boulder Canyon. On the most recent mission, I’d put the jacket on over bare skin between climbing burns – I felt toasty and cozy.

The Powerfly is the middle layer of a four-point Columbia layering system. It’s the layer I can’t seem to take off – I wear it everywhere; even in the comfort of my office as I type.

As a set, the Powerfly is one of several layers that can be worn in unison, including the Extreme Fleece ($80) base layer, and Ultrachange (this is two jackets that fit together, or apart, the Omni-Heat reflective and Omni-Wick EVAP; combined they’re $450, 20oz). The Omni-Heat reflective is a nylon/synthetic liner which doubles as a belay jacket for spring or fall. Omni Dry EVAP is the ultra-light outer shell.

The Omni Heat synthetic jacket has become my go-to jacket for days when I need a mid-weight layer. When I was in Hueco wearing the Omni Heat, I often covered it with the REI Thoroughfare Jacket to keep it from getting scratched and torn on the sharp rocks.

The Omni Dry EVAP is so light that at first I didn’t want to take it mixed climbing because I didn’t want to tear it. It worked without a problem on the ice but I keep it off when dry tooling in the course limestone chimneys. None of these layers take up excessive weight or bulk, and the fit hugs the body.

The author toasty and cozy while climbing in Boulder Canyon.