Hearing aid casing of the miniature type

Claim 1

IN A MINIATURE HEARING AID APPARATUS IN WHICH MINIATURE ELEMENTS ARE ARRANGED WITHIN A PLASTIC CASING, SAID CASING COMPRISING: TWO SHELL PARTS PROVIDED WITH COMPLEMENTARY EDGES PORTIONS FACING EACH OTHER AND ADAPTED TO BE ASSEMBLED INTO SAID CASING, SAID EDGE PORTIONS BEING PARTIALLY AT LEAST APPROXIMATELY LINEAR AND PARTIALLY RELATIVELY STRONGLY CURVED TO FORM RELATIVELY SHARPER BENDS, AND MUTUALLY INTERENGAGEABLE LOCKING MEANS AT SAID EDGE PORTIONS FOR HOLDING THE TWO PARTS TOGETHER IN THE ASSEMBLED CONDITION OF THE CASING AND ESSENTIALLY CONSISTING OF ONLY COMPLEMENTARY UNDER-CUT MEANS OPERABLE TO ELASTICALLY ENGAGE ONE WITH THE OTHER WITH SAID TWO SHELL PARTS ASSEMBLED INTO SAID CASING, SAID COMPLEMENTARY UNDER-CUT MEANS BEING PROVIDED WITH COOPERATING INCLINED SURFACES WHICH ABUT AGAINST EACH OTHER WITH SAID CASING ASSEMBLED, SAID INCLINED SURFACES FORMING AN ACUTE ANGLE, WHICH IS LESS THAN 20* AND LARGER THAN 3*, WITH RESPECT TO A LINE PERPENDICULAR TO THE SEPARATING PLANE BETWEEN SAID SHELL PARTS, SAID ANGLE BEING SMALLER WITHIN THE REGIONS OF SAID BENDS THAN IN THE APPROXIMATELY LINEAR REGIONS OF SAID EDGE PORTIONS.