Wi-Fi Detector Shirt Size M (Medium) - A shirt with a built-in Wi-Fi signal detector Glowing animated shirt dynamically displays the current wi-fi signal strength. Shows signal strength for 802.11b or 802.11g Black 100% Cotton T-Shirt - Size Medium Runs for hours off AAA Batteries (not included) Animated Decal is Removable (with hook and loop fasteners) for Easy Washing Battery Pack is Concealed in a Small Pocket Sewn Inside the Shirt