These are heavy duty hard plastic to fit the shorter chromed sidecover badges used on T160 model from 1975.
A case here of the procuring department getting ahead of the production line, as these were meant for the 870cc T180 Thunderbird III model that didn't make it past prototype stage. Various versions including an isolastic frame by NVT and then an oil bearing frame by the Meridan Co-operative were all rejected as too expensive and/or too hard to launch the new model (funding was drying up fast).
However..., there's nothing stopping you from building one yourself, starting with a pair of these stickers and working forward from there.
A certain Wairarapa lunatic with more time on his hands than most of us... (yes, that's you I'm talking about Dave) went down the NVT route and came up with a Norton flavoured version, looking factory good, as pictured)
And no Virgil, you don't get the rocket with the stickers...
Thunderbirds are go..!