Double-layer water-proof zipper

A double-layer water-proof zipper comprising:

• a first slide, said first slide comprising a loop-like lug, a pull tab coupled to the lug at said first slide, a first interlocking control unit, and a second interlocking control unit, said first interlocking control unit having a substantially I-shaped profile defining a first passage, a second passage and a rear interlocking chamber, the first passage and second passage of said first interlocking control unit being horizontally arranged in parallel and axially forwardly extended from the rear interlocking chamber of said first interlocking control unit, the first passage and second passage of said first interlocking control unit having a transverse width gradually reducing toward the rear interlocking chamber of said first interlocking control unit, said second interlocking control unit is formed integral with said first interlocking control unit at a top side, having a S-shaped cross section defining a first passage, a second passage and a rear interlocking chamber, the first passage and second passage being disposed at different elevations and axially forwardly extended from the rear interlocking chamber of said second interlocking control unit;
• a zipper tape unit closed/opened by said first slide, said zipper tape unit comprising a first zipper tape, a second zipper tape, a first row of teeth and a second row of teeth respectively securely mounted on said first zipper tape and said second zipper tape and respectively inserted through the first passage and second passage in the first interlocking control unit of said first slide;
• and
• a water-proof layer covered over said zipper tape unit to stop water from passing through said zipper tape unit, said water-proof layer comprising a first water-proof tape, and a second water-proof tape overlapped together, said first water-proof tape and said second water-proof tape each having one side edge formed with two longitudinally extended parallel grooves and two longitudinally extended protruding portions respectively raised along said parallel grooves at one side, the protruding portions of said first water-proof tape and said second water-proof tape being respectively inserted through the first passage and second passage in the second interlocking control unit of said slide;
• wherein when said first slide is pulled in one direction, the first row of teeth and second row of teeth of said zipper tape unit are interlocked, and at the same time the protruding portions at one water-proof tape of said water-proof layer are engaged into the parallel grooves at the other water-proof tape, causing the overlapped area between the water-proof tapes of said water-proof layer to be water-tightly retained together;
• when said first slide is pulled in the reversed direction, said zipper tape unit and said water-proof layer are opened.