Dual Control Buttons: The patch on the left chest features two independent control buttons. These typically allow you to separately toggle and adjust the heat zones for different body areas (such as the back/neck versus the abdominal areas). • Three Temperature Settings: Vests of this design generally utilize a color-coded LED system within the buttons to indicate heat intensity (e.g., Red for high heat, White or Blue for medium heat, and Green or Blue for low heat). • Amazon UK • Power Source: It relies on a standard internal USB cable hidden inside a pocket. This cable connects to a portable 5V power bank (not included )