These pigs, called solid cast pigs by some, are available in sizes from 2" to 48" They are almost always made of urethane and offer flexibility both in their performance and capabilities. They are used mainly as sealing pigs but can carry cleaning elements when required. Most styles are one piece or solid cast. Some models allow cups and discs to be changed out when worn or damaged. Hardness can be varied as required. Most can carry pingers, magnets, or other devices.