multi-LED screw-in bulbs which replace real C7+1⁄2 and C9+1⁄4 bulbs and are much closer in brightness than the mini imitations.[citation needed] In the modern Holiday lighting technology has been subject to considerable development and variation since the replacement of candles by electric lights. While originally used during the Christmas holidays as Christmas lights, modern electric light arrays have become popular around the world in many cultures and are used both during religious festivals and for other purposes unconnected to any festivities. Incandescent (midget) or LED-based sets usually have each lamp connected in series to be powered without a transformer in the set. Screw-base C7 and C9 light sets use line voltage (120 volt) bulbs and are wired in parallel. LED-based sets use a current-limiting resistor to reduce the current supplied to each LED. Neon-lamp-based sets have lamps connected in parallel, each with its own current-limiting resistor. Battery-powered sets are also wired in parallel. Some incandescent or LED-based strings use a power supply transformer with lamps connected in parallel. These sets are much safer, but there is a voltage drop at the end of the string causing reduced brightness of the lamps at the end of the set. The reduced brightness is, however, less noticeable with LED-based sets than incandescent sets. Power supplies with integrated plugs may make the set difficult to connect in certain places. A line-operated AC string with a male plug on one end and a female socket on the other end can be conveniently connected end-to-end with other similar strings. The gauge of wire used, current rating of the fuse (if present) and the power consumption of each string will determine how many strings can be safely daisy-chained this way, or whether the end string will have diminished voltage and brightness.