M8 LH x 40mm A4-AISI 316 Stainless Steel Dual Double Thread Screw - 208.516.408

Always drill a pilot hole to prevent wood from splitting and to ease installation. You can use a socket drive to install this item by fitting a dome nut or two nuts locked off together on the end of the thread. The machine thread section can also be fitted directly into the chuck of a drill and this can then be used to drive the fitting into the pilot hole. Keep drill torque settings and drill speed as low as possible to prevent damage to the thread.