Inline inspection pigs use various methods for inspecting a pipeline. A sizing pig uses one (or more) notched round metal plates as gauges. The notches allow different parts of the plate to bend when a bore restriction is encountered. More complex systems exist for inspecting various aspects of the pipeline. Intelligent pigs are used to inspect the pipeline with sensors and record the data for later analysis. These pigs use technologies such as magnetic flux leakage (MFL) and ultrasound to inspect the pipeline. Intelligent pigs may also use calipers to measure the inside geometry of the pipeline.