Cutlass Classic

Hi 
Just joined the site.
i have 2 Cutlass Classics. My first one is a white model and is basically unplayed and in almost new condition. My second one is natural wood and a bit bashed but a fantastic guitar. I think these are brilliant instruments and i don't feel I need any other electric guitars as they do most things well.

I need to do some neck relief one the white one and need the key to do this. Can anyone advise of the size/type I need? I used an allen key on the other Cutlass but this mark the paint work on the head stock.

Thanks for any advice.

Lesm