If the lower slider is raised then the bottom part of the jacket may be opened to allow more comfortable sitting or bicycling.
When both sliders are lowered then the zipper may be totally separated.
In March of the same year, Mathieu Burri, a Swiss inventor, improved the design by adding a lock-in system attached to the last teeth, but his version never got into production due to conflicting patents. The company opted to use Gideon Sundback's fastener on a new type of rubber boots (or galoshes) and referred to it as the zipper, and the name stuck.
The popular North American term zipper, (UK zip, or occasionally zip-fastener), came from the B. The two chief uses of the zipper in its early years were for closing boots and tobacco pouches.
The company moved to Meadville, PA, where it operated for most of the 20th century under the name Talon, Inc.
The clasp locker had its public debut at the 1893 Chicago World's Fair and met with little commercial success.
Judson is sometimes given credit as the inventor of the zipper, but he never made a practical device. Gideon Sundback, a Swedish-American electrical engineer, was hired to work for the company in 1906.
Problems often lie with the zipper slider; when it becomes worn it does not properly align and join the alternating teeth. In 1851, Elias Howe received a patent for an "Automatic, Continuous Clothing Closure".
With separating zippers, the insertion pin may tear loose from the tape; the tape may even disintegrate from use. He did not try seriously to market it, missing recognition he might otherwise have received.