The Manipulator Arms are two mechanical arms stored in the Satellite of Love. Accessed from a panel and button marked "Manos", they can be deployed from a port to manipulate or grab objects outside the Satellite. The arms are controlled from within the SOL with two special gloves, which every move is mimicked by the arms.
The arms are only seen in the second host segment of Mystery Science Theater 3000: The Movie, when Mike Nelson uses them to free the Hubble Space Telescope, which he crashed into moments before. When removing the billion dollar telescope, he accidentally tears the hull open, and then drops it in the atmosphere, thinking it would go back into orbit. The telescope burned up at re-entry.
A similar device, likely an earlier version, referred to as "exo-pinchers" was used by Joel in Women of the Prehistoric Planet to bring a nearby satellite onto the ship.