GEORGE Black Acrylic Slider Collar Size S / 2cm width (43cm) / ¥8,250 (tax included) Unused. Nylon choke collar. This collar tightens when pulled, signaling "No!" It's a tool for communicating commands to dogs who don't understand words, by applying pressure to the neck. Two charms are attached. The charms make a sound when a command is given, and this sound also helps with the command.