I recently completed a 23 day study comparing the ADXL355 to a very high end accelerometer from another company. The ADXL performed very well in terms of magnitude and reliability. In order to match the other accel we had to adjust the set sample rate of the unit. We needed to adjust it by +1.2% which seemed very high. I looked through the spec for a tolerance on the internal clocks but I didn't see something I could convert to allowable tolerance on the rate. The rate was very consistent so I don't think there is internal drift. I am curious what the tolerance of the frequency setting is.