Original: They are characterized by possessing a set of hollow, fixed fangs through which they inject venom, and come in a wide range of sizes, from only 18 cm (Drysdalia) up to 6 m in length (Ophiophagus).
Simplified: They are characterized by a set of hollow, fixed fangs through which they inject venom. There are snakes of different sizes,  from only 18 cm (Drysdalia) up to 6 m in length (King Cobra).