The name for a device used in circuiting multiple lighting instruments into one circuit. It has three female ends and one male end thus allowing you to get "Three for One." Also known as a "three-way" or "multiple branch off." Comes in either molded "W-style": http://www.norcostco.com/wsplicebluntend.aspx OR (becoming rarer each day) as an approx. 3"x4"x1" block: These are still manufactured by Union Connector in both cable-mounted and male-pinned versions. This device is sometimes called a Best Little '______' in Texas "Block." If three fixture s are to be ganged onto one circuit and no Three-Fers are available, two Two-Fer s, one plugged into one of the females of the other, can achieve the same goal.