Flexes with a cloth outer have rubber inner insulation. These have a high temperature rated outer surface. They are well known for their use on irons.

Old cloth insulated flexes are prone to kinking, with the inner rubber insulated wires poking out at the kinks. New cloth insulated flexes have a layer of rubber under the cloth that discourages this from happening and now coming in a myriad of colours to go with old style and antique lights etc to give them a fresh lease of life.

The rubber inner insulation can harden and break at the ends. This is often seen on old cloth flexes. When this occurs the flex can be cut back several inches to reveal healthy flex, and reconnected, if the rest of the flex is still healthy.