The DTT2Z is a safe, cost-effective way to attach deck-railing posts to the deck framing for stronger, safer railings. Because the post is tied back into the deck joists, rather than to the rim joist alone, the connection is stronger than typical through-bolt installations. The DTT2Z is also ideal for guardrail-post connections and lateral-load connections between the deck and house. DTT ZMAX® Galvanized Deck Tension Tie for 2x with 1-1/2 in. SDS Screws (Pack of 1920).