The Nitecore UNK1 is a USB battery charger designed exclusively for Nikon cameras and is compatible with a range of models. Offering dual slots on the front and back of the charger, the UNK1 caters for both the primary and back up batteries, ensuring you have power when you need it most. The charger features a smart charging management system, monitoring battery types, capacities, internal resistance upon charging initiation and automatically applies the most appropriate charging current based on the monitored data. The UNK1 has an LCD display screen which provide feeds on overall charging status, including the charging current, battery voltage and battery level. In addition, the charger monitors the condition of the battery based on the internal resistance upon installation. This is displayed via a BH (battery health) bar which is divided in 3 segments. When a battery has reached its lower health limit, the BH bar will start flashing to indicate the battery should be replaced. The Nitecore UNK1 is compatible with the following Nikon models: D750, D810, D610, D7100, D800, D800E, D7000, D7200, D810A, D600, D3300, Df, D5300, D3X, D5500, D5200, D3200, D5100, D3100.