SLEEPING BAG TERMINOLOGY
The shell contains and protects the insulation, blocks wind, and repels moisture.
A hood is key for keeping warm in cool temps. Look for easy-to-reach cinch cords and Velcro that closes on itself so it doesn’t scratch.
The tube or flap of insulation at the neck opening—called the draft collar—traps heat and prevents drafts; it’s especially important on bags rated to 20°F or lower.
Some bags have a yoke, rather than a draft collar, which is an insulated, U-shaped tube that hangs freely around the neck to block drafts.
Look for a shaped footbox with sidewalls so your feet have wiggle room and won’t press into the insulation to cause cold spots.
The insulation or fill is the lifeblood of any bag. The loftier the fill, the warmer the bag.
Look for a smooth-running zipper with stiffened backing fabric that prevents snagging. Some bags have a centered zipper, which shaves weight and allows you to sit up and perform camp chores.
The insulated draft tube (or sometimes, pair of tubes) lies behind the zipper to block air from seeping through the coils.
Interior chambers called baffles in down bags keep insulation from shifting and bunching up.
Pad sleeves or straps on the bottom of the bag prevent it from sliding off your sleeping pad.
Often found on bags with shorter zippers, foot vents maximize ventilation.