You are correct. The product is a transceiver. By the way, the 4040 product number cited here is a retailers number for the product. It the actual manufacturers product number is IR543.
The other transceiver mentioned in this thread with the antenna is used to receive X-10 RF signals and send X-10 signals over the AC powerline. It cannot be accessed by the Pronto because it doesn't receive IR signals. However, if you purchase X-10 RF wireless controllers you would need this transceiver. The advantage of using RF is that you do not have to be in the same room to control your lighting.
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