Inhibitor band

It's never illustrated how they got one around Rack'n'Ruin, more's the pity.

Neither as uncomfortable nor unsightly as an inhibitor claw, an inhibitor band is a means of restraining a Transformer and preventing them from transforming.

Fiction

Marvel The Transformers comics

Inhibitor bands appeared exclusively in the UK portion of the Marvel Comics continuity.

When Flame captured Emirate Xaaron and the Wreckers to prevent them with interfering with his plan to ignite Cybertron's giant engines, he fitted them with inhibitor bands and kept them captive below Kalis, guarded by the zombie Impactor. However, while the bands prevented him from transforming, they did not impede Springer's leaping ability and he was able to escape from the cell, taking Impactor with him. Legion of the Lost! Subsequently, Xaaron and the rest of the Wreckers were somehow able to escape their inhibitor bands and escape the cell as well. Meltdown!