Energon band

Energon bands are Cybertronian technology from the Armada portion of the Unicron Trilogy continuity family.

Energon bands are simple restraining devices invented by the Decepticons. They respond to the captive's struggling by becoming tighter. Contrary to Megatron's claims, they are not indestructible, as the bands' locks break if hit with a powerful blast of energy.

Fiction

Dreamwave Armada comics

The Decepticon had the Autobots tied up in energon bands. Swindle, who had been betrayed by the Decepticons, freed them by shooting the locks on Optimus Prime's bands. Optimus Prime in turn destroyed the energon bands holding his troops. Armada Free Comic Book Day