Wireless transmitter holder by Zill and Rei+, a leather brand specializing in bands. This is for the BOSS wireless system WL-60 transmitter, WL-60T. It's a custom design, so it holds the transmitter securely. This is a musical instrument store Opus limited edition type, with the "lid" part that secures the transmitter in the case positioned to the side. It's a beautiful item, only used once at home after purchase.