M8 x 50 Coach Bolts + Nuts (Cup Square Hex Bolts) Bzp. Pack 50. Low round head with square underneath to lock into wood. Timber to Timber or Timber to Metal applications. The bolt is inserted i i in pilot hole in material & as the nut is tightened it pulls the square section of the shank into the hole/wood & locks it leaving a low domed head finish.