The radio-flashlight was Rudyard Shelton's signature piece of equipment. Exteriorly, it resembled a crank fashlight and functioned as such, but if the crank was opened it became a mouthpiece and a radio on the inside could be used.
Shelton had it with him in the control room at the beginning of the terrorist invasion, and regularly used it to communicate with people in other areas of Pelvanida. It was the radio he used to call for help, a call that resulted in Cobalt Squad being sent. When Shelton finally left the control room and tried to lead a team to auxiliary control, he used the flashlight during the darker parts of the trip. He also shined the light through the Einstein-Rosen bridge during the final shootout in the hangar. Darwin's Soldiers
Shelton had the flashlight among his equipment he brought on the trip through the Einstein-Rosen bridge, and so an anti-matter copy was created. It became crucial when Shelton used it to figure out the time conversion between Earth/Gamas timescales, allowing him to send them back to Earth. During this mission, it was revealed that the flashlight also had a timer on it.
When Shelton returned in a helicopter during the second invasion, he quickly lost it after the copter was shot down and crashed into Pelvanida's roof. He later returned and retrieved it, and used it to contact James Zanasiu and warn him about the bomb in Pelvanida. (Survival of the Fittest)
During his time in Dragonstorm, Shelton tinkered with the flashlight and attempted to get it to connect to the thought network, but he never got around to finishing the project. This still left a thought transmitter and signal boosting equipment inside the flashlight.
Shelton did not bring the flashlight with him on his DS-1 missions, so when he originally met with James' team in September 2009, he didn't have it with him. He later picked it up during the Battle at Lab 101 and carried it with him, though its usefulness was dimished by the thought network. It did save the lives of him and everyone on DS-2 when they were attacked by terrorists and he used it to boost his thought signal range, and recieve important important from Hans Donitz regarding the enemy planes.
The radio-flashlight became a piece of the Smithsonian exhibit dedicated to the Einstein-Rosen bridge and its creators. ROSS was trapped within it and any visitor who turned the radio on was allowed to speak to him. He despised this, and in 2033 James Zanasiu Jr, Malte Kerzach and Florence Brennan stole the radio-flashlight with ROSS in it. ROSS then programmed the radio-flashlight so that it could read bridge coordinates and scan them, showing the trio if the coordinate set was right or wrong.
The radio part of the radio flashlight was broken soon after, when Pomson hit it with a high-powered slingshot in the Blue Ridge Mountains. ("CS:Breaking Up") The radio-flashlight continued with the trio until James slipped into a coma, and was not used again. ("CS:The Meaning of Love")