You can insert the chain either

• closed in the outlet opening
  or
• opened in both inlet openings

of the slider. Both ways are shown in our video.

When inserting the closed zipper chain into the slider, first push the chain as far as possible into the outlet opening. Then pull the inserted zip fastener back a tiny piece. This way it will be easier to pull the two zip fastener tapes apart with your thumb and forefinger. As a result, the front-most teeth loosen inside the slider and the zip fastener splits as you pull it forward.