Cable insulators are basically insulated item to keep distance with metal and cable. these are mostly made out of porcelain insulation material. rather than keeping a straight shape they are made with rounds . which will break the connection s when water is flowing down.
this particular insulator is used to keep bare ACSR conductor which is attached by a clamp. this equipment is very heave that you have to bring this up with care .
For 33kv line they use 3 rounded insulator in which each round represent 11kv . from counting the rounds you can measure the voltage it carries.
you have to drill a hole most likely 25mm to attach the insulator into the supporting c channel (iron metal bar). you can do it by using magnetic drill .