The US040015 is an ultrasonic sensor of asymmetrical beam patterns, approximates ±80° / 40° for orizontal/vertical, which mostly suits for car reversing aids.
The couple of transducer 250ST/R180 is suited for low cost applications where the minimum measurable distance is a fundamental parameter or anyway for simple detection of people and objects passing
The couple of transducer 328ET/R250 is suitable for outdoor low cost applications where the minimum measurable distance is a fundamental parameter or anyway for simple detection of people and objects passing.
The couple of transducer 328ST16M is suited for low cost applications where the minimum measurable distance is a fundamental parameter or anyway for simple detection of people and objects passing.
The couple of transducer 400ET/R080 is suitable for outdoor low cost applications where the minimum measurable distance is a fundamental parameter or anyway for simple detection of people and objects passing.