Seirus Innovations Thermax Heat Pocket Mitts are the warmest liner for mittens. Thermax gives maximum comfort and wicking to any mitt with a thin, insulating inner layer. Shell: 100% Polyester Cuff: 100% Nylon Machine Wash EXTRA WARMTH - An integrated heat pocket allows you to store a heat pack in the glove for hours of extra warmth VERSATILE - Can be worn as a stand alone lightweight mitt, or as a mitten liner THERMAX MORE - More stretch, more warmth, more wicking, more windblock and incredibly comfortable! FORM FITTED - Cut and sewn to ensure a comfortable fit​​