Brown wall plugs require a 7mm drill bit for installation. The screw diameter for brown wall plugs is typically between 4.0mm to 6.0mm. Brown plugs work best with screw sizes 8 through 12, but can be used for screw sizes 8 through 14. It is important to use the appropriate size drill bit to ensure that the plug is securely anchored in the wall. If you come across a wall plug with an unknown size, you can determine the correct drill bit size needed by comparing the drill bit with the large drill bit hole on the left side of the wall plug strip. The bit should tightly fit into this guide hole.