Wikipedia
ZipBind spines are a brand of binding elements manufactured by the General Binding Corporation (GBC).
The spines are made out of plastic and have 19 rings, similar to a like a plastic binding comb. The hole pattern needed for ZipBind spines to work is the same one used for comb binding and will usually be made through paper drilling. These spines can be opened with a tool that acts like a zipper. The spines can be opened and closed numerous times which allows the user to make changes to his/her documents.
ZipBind spines are designed so that documents bound with them will lie flat. The spine also allows the pages to rotate a full 360 degrees. The spines are available in two sizes. The 3/8" ones can bind up to 55 pages. The 1/2" spines are for documents up to 85 pages long. No machines are needed to use the spines—the user just needs to have properly punched paper.