20-Device AC Charging Towers for Chromebooks - Open Frame, White, 2 Pack (40 Devices Total). Provide high-speed AC charging and secure storage for 40 Chromebooks or tablets in a space-saving form factor designed for crowded rooms. The CST40AC consists of two CST20AC 20-device charging towers. These wall-anchored, floor-standing 120 V charging stations provide high-speed AC charging, secure storage and cord management for as many as 40 Chromebooks, tablets and other mobile devices with a screen size up to 16 inches. These towers are recommended for schools, small/medium businesses, medical facilities, government agencies and anywhere else that uses Chromebooks or tablets on a daily basis.