SINEDY Tea Coffee Cup Mug Warmer USB Heater Pad with Hub Keep coffee/ tea/ beverage warm at 50-60 and enjoy the E-communication at the same time. USB Hub and USB full speed Plug-Play Operation system: Windows98/ 2000/ ME/ XP.IMac, G3, G4 or iBook with free USB port. Size: 10.5cm x 9.5cm x 2.2cm - 4.13inch x 3.74inch x 0.87inch.