Power acoustic vhs player with infrared?

Hi. I just installed a power acoustik vhs player along with a ceiling mount screen. The player came with a bulb-like piece on a long wire with a red 1/8 stereo plug on the end. I could not find anywhere on the player for this plug and thought it was an infrared receiver for wireless headphones,until I took out the headphones and found that they have their own infrared receiver. What is this peice and where does it plug into please? Any help is appreciated Chaim

Thanks. I didn't see the input but I'll check again. You are probably right,if they sent the nsensor there must be a reason. I was thrown off by the plug on the end that looks like a typical headphone or mic plug.