Stemco® Zip-Torq® Axle Nut - Parallel Trailer (400-4723) Zip-Torq® is the latest STEMCO innovation designed to make the roadways safer. With its robust single piece design, Zip-Torq® takes the guess work out of bearing adjustment. Simplified & Fully Unitized Design Single piece design allows installation without special tooling. No clips, keepers, snap rings, or screws to install. Prevents Back Off Integrated locking mechanism prevents back off. Secure Adjustment, Easy Removal Cannot rotate nut by hand after wheel-end adjustment is complete. After locking mechanism disengages, one can remove by hand. Consistent Endplay 2-1-1 adjustment provides consistent TMC recommended endplay measurement between .001"-.005". Highly Compatible Zip-Torq is compatible with most automated installation equipment, so there’s no need to purchase new equipment. Extend Warranty Zip-Torq is offered with STEMCO PPS+ programs, to allow one to package wheel end products to get the best warranty in the industry. Install With Confidence STEMCO offers installation videos and manuals online – available in the STEMCO app and on the website