Accelerometers use a strain gauge to measure not only steps, but the intensity of your movement. With no moving parts to wear out, the NL-series accelerometers are silent and extremely durable. The strain gauge's ability to continue to
 
  count even with a "tummy tilt" makes the NL-series more accurate than the DIGI-WALKER in those who are overweight and obese. Overall, they are the best step counters in the world.