1/2" x 12" galvanized button head spikes. $1.50/each spike (or best offer).
Hot-dip galvanized finish, 1/2" x 1/2" square body, 1" diameter button head (they weigh about 15 oz/each).
With a wedge point, these boat spikes easily drive into large timbers and logs.
They can be used for heavy timber or marine construction. They are also good for landscape retaining walls.