Ziploc is a brand of reusable, re-sealable zipper storage bags and containers originally developed and test marketed by The Dow Chemical Company in 1968, and now produced by S. C. Johnson & Son. The plastic bags and containers come in different sizes for use with different products. The brand offers sandwich bags, snack bags and other bags for various purposes. In 1951, a company called Flexigrip, Inc. was formed to develop and market a plastic zipper, by the same name, based on a set of patents, which it had purchased, of which the inventor was Borge Madsen. The initial products for the Flexigrip and other plastic zippers (such as the sliderless zippers (toptite) that were developed by Flexigrip) were looseleaf binder inserts and flat briefcases. Thereafter, the marketing efforts were directed at packaging products in plastic zipper bags, which turned out to be the principal market for the Flexigrip, Inc. products. In 1961, Flexigrip, Inc. obtained from a Japanese company, Seisan Nippon Sha, who invented the Minigrip-type plastic zipper bag, exclusive manufacturing and selling rights for the United States, based on a series of plastic zipper Seisan patents. A company by the same name was formed to produce and market Minigrip bags.