In 2011, Shure previewed Axient, a wireless management network, which includes features for spectrum management, interference detection and avoidance, frequency diversity, remote control (including remote configuration of wireless units via the 2.4 GHz "Zigbee" WPAN IEEE 802.15.4 based "Showlink" protocol) and the use of Li-ion rechargeable batteries to eliminate the use of ordinary AA and AAA batteries. Shure also previewed "Wireless Workbench" software in conjunction with Axient. This was a desktop application for Mac and Windows designed to monitor and control networked Shure wireless systems, as well as provide tools to coordinate and deploy compatible frequencies. Since its initial release, the application has received numerous updates, and is now available to download for free from Shure's website. They started shipping Axient in January 2012 and it has been used in venues and events such as the 2012 Summer Olympics and Paralympics Opening and Closing Ceremonies in London. In 2013, Shure introduced the BLX wireless system to replace the Performance Gear and PGX wireless systems) and the GLX-D wireless system, which operates in the 2.4 GHz frequency band. Personal monitors Shure entered the personal monitoring system category in 1997 with the introduction of the PSM 600. In-ear personal monitoring systems enable a performer or public speaker to monitor audio separately from the amplified sound for the audience. Prior to in-ear monitoring, this was usually accomplished by monitor speakers placed on the stage and oriented toward the performer or speaker and away from the audience, and usually with its own separate "monitor mix" of audio. An in-ear monitor system isolates the monitor mix without the interference of other background sounds, and reduces the risk of other complications like feedback. In 2000, the Shure PSM 400 Personal Stereo Monitor system was awarded a TEC Award. Shure introduced the PSM 900 Personal Monitor System at the 2010 Winter NAMM Show. Earphones Shure also offers in-ear monitor-styled earphones as a part of a personal monitor system package or as an independent purchase, as these earphones are also suitable for music listening on portable audio devices such as MP3 players. Headphones Shure started offering around-ear headphones in May 2009, and since then expanded their lineup to cater to different listening needs, from basic listening to audiophile-demanding listening. In October 2014, Shure began to offer on-ear, portable headphones in semi-open back and closed back designs. The closed back model is optionally available with an inline microphone and