The Four Barrier Magnetic Thickness tool (MBTT4) is designed to evaluate the corrosion status of the well completion such as tubing and/or casing of 3rd and 4th barriers. This evaluation is achieved by emitting and receiving electromagnetic fields, followed by data computation using specialized software. A Memory and SRO Magnetic Thickness tool requires no preparation of well completion such as a scraper run. It is a stand-alone survey aimed to save time and cost for the mature wells integrity evaluation.