SPAX T-Star Washer Head construction fasteners with yellow zinc coating are intended for interior structural wood-to-wood connection applications. These fasteners are designed with a low profile large diameter wafer head for applications requiring additional surface area under the head for superior pull-down force. Ideal for framing attachment and multi-ply beam applications. Cold-rolled "carbon steel" wire, heat treated to grade 5 durability and plated with a yellow zinc finish to prevent red rust. "Yellow zinc" is tested and recognized for use in above ground contact pressure treated lumber for interior dry/damp general construction applications.