Whirlwind Qbox is a multipurpose testing device for checking audio lines. It can send or receive audio signals at mic or line levels, detect the presence of phantom or intercom voltage, and act as a 2-way intercom. The Qbox features a built-in speaker, stereo headphone jack, XLR and 1/4-inch jacks, and a TT jack for passive monitoring. It is powered by a 9V battery or a battery eliminator. With its compact size and versatile features, the Qbox is a valuable tool for audio professionals and hobbyists alike.