This flexible LED Strip are sold at continuous 16.4 feet length. You are able to cut at every 3 LEDs. LED Strip can be cut to size at marked intervals and rejoined by a simple solder or solder less connection.Designed for both the lighting professional and amateur, this LED Strips are very easy to install and uses 3M Tape backing for easy mounting. Just peel and stick to any clean flat surface.These 12 volt LED Strips are sold in one reel of 16.4 feet (5 meters) increments. If you select a quantity of "1", you will get a roll of 16.4 feet (5 Meter) LED Strip. If you select a quantity of "3", you will get 3 rolls of 16.4ft./roll total length = 49.2 feet (15 Meter), and so on.LED Strips require a Power Supply with a 12V DC output.You can find the Power Supply needed for your LED Strip by multiplying the LED Strip Length with Power Consumption/ Meter (3.28Ft.)Example: LED Strip Length = 5 Meter (16.4Ft.) Power Consumption = 4.2W / 1Meter (3.28Ft.)Power Supply needed = 5 x 4.2W = 21W = > you will need a Power Supply with equal or grater than 21 Wattage output