fiber glass nylon hinges the ladder is insulated to prevent the user from electrical shocks in the event the ladder comes into contact with electrical wiring application_number US 11402287 A description the ladder in this invention as shown in fig1 consists of six hinged joints 1 eight uprights 2 twelve rungs 3 and three connectors 4 as its main parts hinged joint 1 consists of a male hinge 11 and a female hinge 12 made of insulation material fiber glass nylon the male hinge 11 as shown in fig1 and 2 has precut teeth 111 and a screw inserted in the center the threads of the screw for the male hinge on one side of the upright is left handed the threads of screw for the male hinge on the other side of the upright is right handed the handle of the male hinge has multiple grooves 113 cut inward the female hinge 12 as shown in fig3 and 4 has precut teeth 121 and multiple grooves 123 similar to those in the male hinge the teeth are cut to mesh with those in the male hinge as shown in fig1 and 12 the screw 112 of the male hinge is to be inserted in the axle hole 122 in the center of the female hinge 12 the upright 2 as shown in fig5 and 6 is made of aluminum it is shaped by pressing it is hollow with a lengthwise inner hole its ends have 10 grooves punched in to fit the corresponding grooves 113 of the male hinge 11 or the grooves 123 of the female hinge 12 when the handle of the male hinge 11 or the female hinge 12 is inserted in the.