The KFW gages have the surface covered with a special resin for waterproofing. The waterproof structure enables these gages to serve for outdoor or underwater measurement merely by being bonded to measuring objects The insulation resistance shows virtually no deterioration even after 100 hours of use under an underwater pressure of approximately 10MPa (100kgf/cm²). In addition, the covering resin is flexible enough to enable easybonding to curved surfaces.