Any idea what the name of this is?

[Curtis]

Need one of a different size to cover an electrical connection on the bike when not in use

[National_Treasure]

rubber grommet, might be plastic but its a grommet.

[timebandit]

Thats harry hill with a black eye that is.

[Alighieri]

To me is just a rubber dust cap

[me_groovy]

https://www.ebay.co.uk/itm/5pcs-Universal-Car-Cigarette-Lighter-Socket-12V-Outlet-Lid-Waterproof-Cover-Cap/372299109975

[Pinhead]

Hi
It’s a black rubber thing
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.
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Pin