These date back to the time of the use of standard diving dress. This is common for free-flow helmets and was part of the standard diving dress system. This was technically a self-contained underwater breathing apparatus based on the standard diving dress. Klingert designed a full diving dress in 1797. The full standard diving dress can weigh . This equipment is the modern equivalent of the historic "Standard diving dress". Powell penetrated into the cave, reaching the seventh chamber, using standard diving dress. All diving dress is to be used exclusively in drinking water. The standard diving dress requires an assistant to help with dressing in and out. Standard diving dress has largely been superseded by lighter and more comfortable equipment. For a long time navies used the heavy standard diving dress for underwater work. German-born British engineer Augustus Siebe developed the standard diving dress in the 1830s.