A GRK Fastener looks like a long screw at first glance, but it is specially designed to join timbers together tightly with less torque than is needed for a lag bolt.
A GRK Fastener is much thinner than a lag bolt, but it is superior in function and much easier to use in a post and beam structure. The threaded end of the fastener screws into the connecting timber. A small reverse thread section makes a larger hole so the smooth shank near the head can slide smoothly through the near timber, allowing both timbers to suck together tightly and with less drag than a lag bolt.
The fasteners used on the carport we just finished in Castlegar were 12″ long with a 1/4″ diameter.