In addition to offering all the same features at the single-sided version, the PRECISION 3+ PRO will allow you to view advanced metrics like left/right balance, pedal smoothness, torque effectiveness, and thereby providing you with the most accurate power numbers for training and racing. The decrease in expected battery life from 800-hrs (single-sided power) to 500-hrs with the dual-sided PRECISION 3+ PRO is simply a reflection of the added functions required by the paired power meters.