The EZL2020-20L from Sennheiser is a storage case and charger designed for Tour Guide systems. The metal case can hold up to 20 HDE2020-D-US stethoset receivers, and also has bays to hold an SK 2020-D transmitter and extra battery. The case can charge all of the system components in as little as 2.5 hours, and has safe recharging with temperature monitoring. A copy button allows you to set the channel on a single receiver, push the copy button, and automatically set the channel on the other docked receivers.