Which zipper works best on a down jacket?

Q: Which zipper works best on a down jacket?

A down jacket usually takes a size 5 nylon coil separating zipper with an open-end bottom and an auto-lock slider; parka-length bodies above roughly 80 cm should carry a two-way slider as well. Coil is preferred to molded plastic here because it stays flexible when the shell is cold and compressed, and it survives the repeated squashing of a packed jacket. Ultralight 800-fill styles often drop to a size 3 coil to save weight, but the tape then needs a stabilizer so the fine shell does not pucker.

• Size 5 coil for standard fill weights, size 3 for ultralight shells.
• Open-end construction with a bottom box and pin, plus a storm flap behind the tape.
• Waterproof versions use a size 5 PU-coated reverse coil with a matte finish.

The common pitfall is a slider without a lock: the zip creeps open whenever the wearer bends, and the flap no longer covers the gap. Metal teeth are the other frequent mistake, since they add weight, conduct cold and abrade the shell along the fold line.