AES 256-bit encryption for applications for which secure transmission is needed Proprietary Shure Gain Ranging optimizes the system’s dynamic range for any input source, eliminating the need for transmitter gain adjustments Optional Shure SB900B lithium-ion rechargeable battery pack provides over 12 hours of battery life, precision metering in hours and minutes, and zero memory effect External charging contacts for docked charging (with the SBC200 Dual Docking Charger) Transmitter Mute Mode repurposes the On/Off switch into a mute switch, enabling audio muting while preserving RF channel presence Backlit LCD with easy to navigate menu and controls Rugged metal construction Frequency and power lockout The ULXD/K11 is a handheld wireless microphone transmitter compatible with ULX-D Wireless Systems.