Retrievable tools, sometimes known as "Slim Tools", can be retrieved and replaced using wireline through the drill string. This generally allows the tool to be replaced much faster in case of failure, and it allows the tool to be recovered if the drillstring becomes stuck. Retrievable tools must be much smaller, usually about 2 inches or less in diameter, though their length may be or more. The small size is necessary for the tool to fit through the drillstring; however, it also limits the tool's capabilities. For example, slim tools are not capable of sending data at the same rates as collar-mounted tools, and they are also more limited in their ability to communicate with, and supply electrical power to, other LWD tools.