1. THE IMPROVEMENT OF A SWITCH AND BATTERY HOLDER ASSEMBLY COMPRISING THE COMBINATION OF A HOUSING FOR ELECTRICAL CIRCUITRY HAVING A PAIR OF OPPOSED WALLS DEFINING A RECESS THEREBETWEEN, A BATTERY HOLDER POSITIONED FOR SLIDING AND PIVOTAL MOVEMENT WITHIN SAID RECESS, SAID BATTERY HOLDER BEING FORMED WITH A CENTRAL APERTURE FOR RECEIVING A BATTERY AND HAVING A PERIPHERAL EDGE CONTOURED TO DEFINE A PLURALITY OF PERIPHERALLY SPACED CAM MEMBERS, A FIRST POWER CONTACT SECURED TO ONE WALL OF THE HOUSING AND ADAPTED FOR ELECTRICAL CONTACT WITH ONE TERMINAL OF THE BATTERY, A SECOND POWER CONTACT SECURED TO THE OTHER WALL OF THE HOUSING AND ADAPTED FOR ELECTRICAL CONTACT WITH THE OTHER TEMINAL OF THE BATTERY, AND OVER-CENTERED SPRING MEANS SECURED TO SAID BATTERY HOLDER AND TO SAID HOUSING AND COOPERATING WITH SAID PERIPHERALLY SPACED CAM MEMBERS ON SAID BATTERY HOLDER FOR ENABLING SAID BATTERY HOLDER TO BE SELECTIVELY POSITIONED AND POSITIVELY HELD IN ITS SWITCH-ON CONDITION WHEREIN BOTH OF SAID POWER CONTACTS ARE IN ELECTRICAL CONTACT WITH THE BATTERY TERMINALS OR IN ITS SWITCH-OFF CONDITION WHEREIN AT LEAST ONE OF SAID POWER CONTACTS IS DISENGAGED FROM ITS ASSOCIATED BATTERY TERMINAL, SAID OVER-CENTERED SPRING MEANS AND SAID PERIPHERALLY SPACED CAM MEMBERS FURTHER SERVING TO ENABLE SAID BATTERY HOLDER TO BE SELECTIVELY POSITIONED AND POSITIVELY HELD IN EITHER ITS OPERATING POSITION WITHIN SAID RECESS OR IN ITS BATTERY REPLACEMENT POSITION OUTSIDE OF SAID RECESS.