Screw size for fog light adjustment

[brianw0048]

I’ve been getting flashed a lot lately when I run my fogs so I was messing with them yesterday. The driver side is missing the adjustment nut on the backside. I’m lighting up tree tops when I turn the fogs on.

Does anyone know what size that screw is? I’m thinking just run to Lowe’s and grab a wing nut that would fit.

Thanks.