They are mini led strip lights with led components pre-mounted on well designed pcbs. Flexible wires, easy-to-mount and easy for installation. They are widely used for letter channel lights, backlights and advertising lights. Now, they are also more and more popular with auto / carl led interior and decorative lights. Widely used / available low voltage 12 voltage dc make them easier to work with your project. If you are a designer, you would choose them; if you are a lighitng contractor, you would choose them and if you are a DIY-er, you would choose them.