from 120 to 130 of the outside diameter of the body portion 52 for example in order to engage a container mouth having an inside diameter of from 0 625 to 0 700 inch 1 59 to 1 78 cm an elastomeric diaphragm of substantially the following dimension is recommended length overall 3 00 inches 7 62 cm length tip portion 0 50 inch 1 27 cm length body portion 1 50 inches 3 81 cm length rear portion 1 00 inch 2 54 cm o d body portion 0 60 inch 1 52 cm i d body portion 0 42 inch 1 07 cm o d rear porotion 0 72 inch 1 83 cm i d rear portion 0 375 inch 0 95 cm it has been common practice to apply coatings or the like to containers by electrostatic means generally speaking an electrostatic coating system includes a spray generator from which the coating composition emanates in the form of very finely divided particles the particles are passed near a high voltage probe or electrode whereby an electrostatic charge is induced on the particles in order to assure deposition of a uniform adherent coating to the container it is preferable to provide a means of maintaining a potential difference between the spray particles and the container one such means being illustrated in fig4 and 4a fig4 and 4a depict a diaphragm 60 similar to the diaphragm shown in fig3 the diaphragm 60 being adapted and modified to assure maintenance of the requisite potential difference between the charged spray particles and the container in the following.