Use our Hole Saw with Arbor for preparing posts for installing the Titan Wood Post Anchor. The circular cut guides the sharp-edged tube into the post. The 1-¼" saw is for the 4x4 post anchor.
The depth of the saw is only 1-7/8" but don't let that fool you. The tube on the post anchor is longer and is intended to be driven down far beyond the depth of the hole saw kerf cut. Then drive the tube and base of the post anchor flush to post with a 3 lbs short handle sledge hammer.