The external casing holders in the USA in well-drilling play a vital role in supporting the string of the pipe to remain the hole open when they lock on the saddle and a small portion is inside of the casing. Manufacturers can make the external casing holders from several different materials such as steel, plastic, or even cast iron. The external casing holders have two main jobs. Number one is holding the pipe of a string while keeping it upright and keeping the hole open after tripping.