an electrical contact modifier is configured to allow the use of a “ single - element ” medium base light bulb in a three - way lamp holder / switch . the device allows the three - way switch to replicate the “ off - on ” functionality of a standard one - way light switch . the apparatus may be implemented as a single - socket bulb extender , or alternately , a device that is concealed within the lamp holder body and / or attached to the base of a one - way “ single - element ” light bulb .