Sliding mechanical closure with color position indicator

The present invention provides a flexible storage bag having an opening and a color indicating element adjacent to the opening, a mechanical interlocking seal for closing the opening, and a slider for sealing the mechanical interlocking seal. The slider includes an aperture, and the color indicating element is viewable through the aperture when the slider reaches a position along the mechanical interlocking seal to register the aperture with the color indicating element. The color indicating element is preferably positioned adjacent to an end of the mechanical interlocking seal, preferably positioned so as to indicate that the mechanical interlocking seal has been fully closed. The color indicating element may be a plastic insert of a different color than its surroundings or may be printed or painted in place.