Attaches with velcro to the shoulder arch at the bottom of the ALEXA, ALEXA Plus, ALEXA Plus 4:3, ALEXA Studio, ALEXA XT, ALEXA XT M Body, ALEXA XT Plus, ALEXA XT Studio, ALEXA SXT EV, ALEXA SXT Plus, ALEXA SXT Studio, ALEXA SXT W or ALEXA LF.