Truss rod adjustment on a Thunderbird IV - which tool?

[Clarky]

Hi all, just bought a virtually new (Oct;09) Thunderbird and there was no truss rod adjustment tool. Please can anyone tell me which type of spanner/wrench I need to adjust the TR as I want to fit lower tension strings and the buzzing is awful right now? Many thanks

[rd_artist]

an allen wrench will do just fine.