In episode 116, Adrian Gecko is shown setting this card onto an electric box that is connected to the security system as he goes through the air vents. In the next episode, Adrian confronts Thelonious Viper and activates this card to set it off and destroy the box in order to prevent Viper from dueling Jaden Yuki. This action activates the permanent lockdown mechanism of the security system.
In episode 119, Adrian activates this card to deactivate the monitors and distract Yubel long enough for him to escape from her grip and subsequently escape from the lab.
In episode 127, Echo planted a bunch of copies of these cards around the "Rainbow Dragon" tablet and threatened to Maximillion Pegasus and Chancellor Sheppard that she would destroy the tablet if they come any closer to the tablet by activating the detonator. She did not detonate them however as Pegasus successfully got his guards to hold Echo down and retrieve the tablet while she was incapacitated.