XC-Tracer mini II
XC Tracer Mini II is an acoustic variometer powered by a solar cell. The lag-free indication of lift / sink makes it much easier to find and core thermals than when using a conventional variometer. Compared to the legendary XC Tracer the sensor data fusion got vastly improved, making flying in thermals even more convenient.
XC Tracer Mini II has a built-in solar cell that delivers 3x more energy than is needed for running the device (when oriented perpendicular to the sun). The surplus energy is stored in a lithium polymer battery. The variometer will run for 20 hours with a fully charged battery without any sun. And the good thing is that you can modify the tone settings as you wish, please check the tone simulator here.