Two-way zippers (such as those we use on our expedition-weight parkas, down pants, and on virtually all of our sleeping bags) can be difficult to get used to, especially when they are new. In order to keep them from getting stuck, make a habit of pulling the tongue of the zipper track (the side without a slider) into both sliders as far as possible, until the metal end is completely inserted into the second slider. Bring the two zipper sides together upstream of the slider and gently guide the main slider up, keeping any fabric out of the zipper track. If the zipper seems a little sticky, try applying a zipper lubricant (or even a little chapstick) along the zipper track to ease the slider along. Over time, the zipper will wear in and move along the track more easily. If your zipper is already stuck, don’t try to force it further. Back the zipper out as gently as possible and carefully tug out any snagged fabric until the zipper is fully disengaged, then rezip as above. Remember to fully zip the garment or bag together before engaging the second slider, or else the fully-functional zipper will appear to separate.