I have not seen this interface but it looks like a 2 prong freewheel tool should fit in there.
Thanks, tried it but the prongs on the freewheel tool are too wide sadly!
@MCamb started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
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I have not seen this interface but it looks like a 2 prong freewheel tool should fit in there.