Bolts Nuts Screws Australia’s hexagon head Class 4.6 grade coach screws are manufactured to Australian Standard AS1393. Hexagon head coach screws are available in corrosion protection coating bright zinc plated and hot dipped galvanised and can be used for heavy duty general purpose construction fastening of timber to timber and timber to steel. Can also be used as medium duty expanding masonry fixings when used with nylon wall plugs. Bright zinc plated for corrosion protection and suitable for internal use in untreated timber. Hot dipped galvanised for maximum corrosion protection and suitable for external use in treated timber.