Heatherwick first designed the best-selling Zip Bag, a handbag constructed of a long zipper. Mom jeans have excess space in the zipper, crotch and leg areas. Modern dry suits have a watertight zipper for entry and exit. Jackets may have a full or partial front zipper, or none at all. Variants include the ascot, bow, bolo, zipper, cravat, and knit. Another type of entry featured a rubber tunnel that protruded through a non-watertight zipper. The outer (externally visible) zipper was a conventional metal toothed slider for mechanical restraint. The protein is a member of the basic helix-loop-helix-leucine zipper (bHLH-Zip) transcription factor family. Catsuits frequently close by means of a zipper at the front or back. The enclosure often has a side opening with a zipper. This chain of leucine residues forms the leucine zipper motif. The suit was joined by a concealed zipper and subsequently modified. A leucine zipper (or leucine scissors) is a common three-dimensional structural motif in proteins. In addition, it contains a polyglutamine tract, a zinc finger and a leucine zipper. This allows the bacteria to invade the cells through the zipper mechanism.