5/16" x 3" Zinc Plated Steel Wej-It Anchors WAS-315 (100 pcs.)Type: Anchor Bolts
Drill Size: 5/16"
Type: Wedge Anchor
Box of 100.
All mechanical bolts have a wedge arrangement at the end. Tightening the bolt results in a wedge being driven up against a sleeve. This jams the end of the bolt, and provides the strength.