These thru-bolt plates are 2-1/2" x 3-1/2". The round rod welded to the plate has a 1-1/4" outside diameter and is 3" long. This piece fits into the pre-drilled thru-bolt hole that runs through the log walls. An 1-1/2" Self-Feed Bit can be used to widen the thru-bolt hole to accommodate the plate rod. The builder secures it into the bottom of the base log course and stacks the wall. When the wall logs are stacked, the pre-drilled thru-bolt holes are lined-up and a 1/2" threaded rod is dropped in from the top. The tapered top allows the threaded rod to center properly and start. May be used in conjunction with Thru-Bolt Springs and Thru-Bolt Washer Plates. Sold individually.