router bit for lokbox plugs

i was wondering what kind of bit is used for installing lokbox plugs? i havent seen any pictures of the underside of a plug yet. thanks

1/2 inch diameter, 4 inch overall length 2 flute.

And the recommended router -

Most shops use this bit already for doing longboard boxes.

Manufacturers can purchase the whole kit from Rainbow fin company, and the router comes equipped with a template guide and bit already installed, ready to rout. Also included are Jig plates for doing Fins Unlimited 10 1/2 center boxes

Rainbow 831-728-2998