theT34 non-coded heart rate transmitter wirelesslytransmits data without the need for conductive gel and offers an enormous battery life of up to 2,500hours of continuous usage,Featuring an adjustable elastic strap and can be removed and is washable–allowing u to keep your sensor free of bacteria and fresh for you workout Water resistant up to 30meters ECG accuracyUp to 2,500 hours of usage Non-user replaceable battery Adjustable medium size elastic chest strap (25-54 inches)Open but never used