The zip fastener was first imagined in the 19th century, by American Helias Howe. It was patented 40 years later by inventor Whitcomb Judson. The patented name was "zip®".

The success story took off in 1921, after improvements made by Gideon Sundbac, an engineer for the Universal Fastener Co. Ever since, its use is widespread for clothing and equipment.

A zip is made of two strips of fabric with tooth down one side, and is fastened and unfastened with a slider. Because the teeth on each strip are offset, the slider clips them together to join the two strips.

Zips are an essential element for bag solidity, so Strenfit subjects them to intensive testing to guarantee correct operation and solidity.