Beware when you are purchasing a 12 lead ECG from this company. It comes with electrode bulbs not disposable electrodes to apply to the patient. Customer support does not respond to your email immediately takes about 2-3 days. I do not recommend this company. Currently having trouble getting refunded. They don't provide you with shipping label return. You have to wait for a shipping address that you have to pay for after being dissatisfied with their product! Please look at the products carefully before purchase!