Features: BLD1 System - Automates charge amplification & reduction on li-ion cells Input-Power Autonomous Regulator integration (no more stressing USB power adapters or ports) Compatible with ALL li-ion cells from as short as 30mm to as long as 73mm LED indicator that reports color and blink variation for quick/easy readout PCB/PCM3 compatible so even protected cells aren’t left out in the cold Protection 101: A] over charge; B] short-circuit; C] wrong battery type detection; D] reverse polarity Specifications: 4 Bay Charger 2.0A x 2, 1.0A x 4 / 1A x 2 & 0.5A x 2 (4A Max Combined Output) Completely automated with LED charge status indicators Compatible will all Li-ion cells from 30mm to 73mm Multiple protection features (over charge, short-circuit, wrong battery type detection and reverse polarity Package Contents: Hohm School battery charger USB power cord User Manual Hohm Tech Hohm School Battery Charger These Hohm School Battery Chargers by Hohm Tech are fully autonomous and are full of safety features, with chargers that hold either two of four batteries and are compatible with 18650,20700,21700. The Hohm School Battery Charger by Hohm Tech is a fully automated and is equipped with the BLD1 system which automates the step up/down output so both small and larger cells charge at the proper rate. Even li-ion batteries with or without PCB/PCM3 are easily balanced to the correct voltage. This ensures today\'s small li-ion batteries chemistry integrity is not compromised, allowing them to get a full life cycle.