Jika-tabi shoes in some industries, many workers prefer them for the softness of their soles. This gives wearers tactile contact with the ground, and the concomitant gripping ability lets them use their feet more agilely than rigid-soled shoes allow. This is useful for workers who traverse girders on construction sites and need to be sure what is under their feet. Carpenters and gardeners wearing these boots can, if they wish, use their feet as an extra pair of hands, for example to hold objects in place. There is also a line of knee-high all-rubber jika-tabi that is used by workers in
Supernumerary body part considered to have lost much or all of their original function through evolution. These body parts can be classed as additional to the required functioning of the body. In human anatomy the vermiform appendix is sometimes classed as a vestigial remnant. Prosthesis is an artificial extension that replaces a body part, and cybernetics is the study of computer technology in relation to organisms which can include replacement or additional body parts. Body integrity identity disorder (BIID) is a psychiatric disorder in which a person thinks that they have one or more additional limbs than they should, despite having two arms