The Relife XA3 Pro Fast Charge Detector is a pro-grade USB tester with a 1.77‑inch color TFT display that shows real-time voltage, current, power, and data line (D+/D–) readings. It supports PD, QC2.0/3.0, SCP, AP2.4A, and DCP protocols, handles up to 6.5 A and 156 W, and offers ultra-high precision (0.00001 resolution) for accurate diagnostics—ideal for repair techs and power users.