“In most designs the biasing of the flexible cover material of the hose is designed to be small compared to the biasing caused by the spring. However, in some designs, for special purposes, the cover material may represent a significant portion of the bias force. In fact, if desired, the hose may obtain all its biasing force from the cover material, and not need a separate metal or composite spring at all.”
“[…] Even the hose cover material itself can be used as the biasing means if made of a resilient material that provides consistent restoring force. The biasing spring(s) can also be placed on the interior or exterior of the hose. Even elastic bands can be used to bias a linearly retractable hose. […]”