A clever battery terminal clamp, which releases it’s grip on the terminal post as you tilt the cover upwards, (& tightens it’s grip as you push the cover downwards), enabling the battery to be disconnected quickly without the need for any tools.
It has blue plastic cover and is for the NEGATIVE terminal.
This clamp fits a standard 16mm round negative post as used on most European cars, as long as it is in good condition (and has not significantly reduced in size). It will not fit the smaller Japanese type battery posts or the square ‘ford’ type posts.
Many French classic cars have earthed components (such as battery mounting brackets) very close to the positive battery terminal. For this reason, when disconnecting a battery, always remove the negative/earthed terminal first. When reconnecting a battery, always connect the live terminal first and ensure that it is not touching or close to any earthed component, before connecting the negative/earthed terminal.