As the name denotes, NCU transducers are truly non-contact.  They are not meant for contact with anything or for water immersion.   Do not touch the face of NCU transducers with your fingers or with anything.  By doing so you will not damage or reduce the transducer performance.  It is just not good practice to touch the transducer face.   Temperature resistance: -20 to 65° C.   Humidity: Not recommended >90% RH.   Should you require, environment-proof NCU transducers are also offered.  Please specify, or consult Ultran.  Environment-proofing may reduce the transducer efficiency between 3 to 6 dB.   NCU transducers, just like the other ultrasonic devices, are also based upon piezoelectric materials.   NCU transducer construction is mechanically sound and robust.   Since the efficiency of NCU transducers is extremely high, it is not necessary to excite them with too high power.  If they are, they too will become hot and susceptible to damage, just like any other piezoelectric device.  If you need any assistance please contact Ultran.   When not in use, store NCU transducers in cool and dry environment.     If you have any questions or require assistance, please contact us.