An apparatus and system for measuring material thickness of a test object. In one embodiment, the apparatus can include a measurement probe that can have a plurality of transducer elements that can include transmitter elements and receiver elements arranged, respectively, in on a first side and a second side of a gap. The first side and the second side can form a scan area with at least one active group that can have at least one transmitter element and at least one receiver element, which can be separated from the transmitter element in a spaced relationship.