The LHi 954 and LHi 958 pyroelectric infrared-detectors have been a world standard for more than 10 years. They both are dual element types with FET in source follower connection. The LHi 954 detector is available in TO-39 housing with standard infrared filter whereas the LHi 958 is the same detector in a TO-5 housing with standard infrared filter. It offers a highly stable responsivity with excellent common mode performance (match) and low noise .