A word to the wise if you're not already aware, the distance one can get away from the transmitter is not even close to the stated value. They work great when close to the transmitter but once one gets to the other side of the home or outside, the reception falls like a stone. Depending on the location of the transmitter and overall transmitting conditions, the headsets can be used outside; SONY better than Sennheiser. Of course, the closer to the transmitter, the better. Line of sight is better than on the other side of two or three doorways. Also, I find they're easily interfered with when used in close proximity to an operating microwave oven. As to needing to replace the batteries, the rechargeable batteries in our units are the original batteries and after several years, they're still going strong. Other than those two warnings with an additional notation, I can't say enough good about the described models.