Campagnolo has updated their EPS power unit charging system. The V4 charging unit is compatible with EPS V2, V3 and V4 Units. The "power unit" is the battery system. The EPS V3 and V4 Power Unit Charger connects via EPS cable to either a connected junction or a power unit itself, then uses AC power a 120v (with 240v capability for international use). You receive the charging unit with EPS connecting cable, BUT you need to purchase the Campagnolo EPS Power Unit Cable (US Standard) separately. Search under Excel part number# 100037.