The Engineering transport tool (ETT) was a rifle shaped piece of transporter technology used by Starfleet. It allowed the user to tag and transport a targeted object or person from one site to another. It could also be used to destroy drones.
While attempting to get around obstacles in destroyed sections of the frontier starbase, James T. Kirk and Spock used the tool extensively. They also used it to access succesive levels of the relay tower. (TOS video game: Star Trek)