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PHONE HOTLINE: 800-346-4296 E-MAIL: sales@hayn.com
Contact Us
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Stud Tensioning Internal Adjuster System

The Hayn Stud Tensioning Internal Adjuster System is a simple, economical Concealed Thread cable rail tensioning solution that hides the adjustment mechanism inside the post for a clean exterior appearance, available in machine swage, Hayn Grip, and Handy Crimp configurations for wire sizes from 1/8" through 1/4" imperial and 3mm through 6mm metric.

Strong Where It Matters

Structural Tension Rod Systems

Tensioning is performed from inside the post using a 3/16" hex key wrench, keeping all adjustment hardware out of sight and maintaining the clean post face that the Concealed Thread system is designed to deliver. Each stud tensioner provides 3/4" of adjustment range with a maximum run length of 20 feet per end — doubling to 40 feet when stud tensioners are used on both ends of the run, and extending further with Intermediate Turnbuckle Assemblies for longer spans. Stair angle compensation is handled separately with Bevel Washers or Adjust-A-Ball hardware; see the Angle Compensation and Termination Accessories page for compatible options. 
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Machine Swage – Factory Assembled to Field Dimensions

Part # Wire Size Thread Size L-Length C-Fully Closed O-Fully Open B-Body Diameter Adjustment Range Max. Run Length Each
ST06A18 1/8″ 1/4-28 1-1/2″ 1-5/8″ 2-3/8″ 5/16″ 3/4″ 20′
ST06AM03 3mm 1/4-28 1-1/2″ 1-5/8″ 2-3/8″ 5/16″ 3/4″ 20′
ST06A532 5/32″ 1/4-28 1-1/2″ 1-3/4″ 2-1/2″ 5/16″ 3/4″ 20′
ST06AM04 4mm 1/4-28 1-1/2″ 1-3/4″ 2-1/2″ 5/16″ 3/4″ 20′
ST06A316 3/16″ 1/4-28 1-1/2″ 1-3/4″ 2-1/2″ 5/16″ 3/4″ 20′
ST06AM05 5mm 1/4-28 1-1/2″ 1-3/4″ 2-1/2″ 5/16″ 3/4″ 20′
ST08A532 5/32″ 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′
ST08AM04 4mm 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′
ST08A316 3/16″ 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′
ST08AM05 5mm 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′
ST08A14 1/4″ 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′
ST08AM06 6mm 5/16-24 1-1/2″ 1-3/4″ 2-1/2″ 3/8″ 3/4″ 20′

Hex key wrench size: 3/16″ for all versions listed.

Hayn Grip™ – On Site Install

Part # Wire Size Thread Size Length C-Fully Closed O-Fully Open B-Body Diameter Adjustment Range Max. Run Length Each
ST06A18-HG 1/8″ 1/4-28 1-1/2″ 2-1/8″ 2-7/8″ 5/16″ 3/4″ 20′
ST06AM03-HG 3mm 1/4-28 1-1/2″ 2-1/8″ 2-7/8″ 5/16″ 3/4″ 20′
ST06A532-HG 5/32″ 1/4-28 1-1/2″ 2-1/8″ 2-7/8″ 5/16″ 3/4″ 20′
ST06AM04-HG 4mm 1/4-28 1-1/2″ 2-1/8″ 2-7/8″ 5/16″ 3/4″ 20′
ST08A316-HG 3/16″ 5/16-24 1-1/2″ 2-1/8″ 2-7/8″ 3/8″ 3/4″ 20′
ST08AM05-HG 5mm 5/16-24 1-1/2″ 2-1/8″ 2-7/8″ 3/8″ 3/4″ 20′

Handy Crimp™ – On Site Install

Part # Wire Size Thread Size C-Fully Closed O-Fully Open B-Body Diameter Adjustment Range Max. Run Length Each
ST06A18C 1/8″ 1/4-28 2″ 2-3/4″ 5/16″ 3/4″ 20′
ST06A316C 3/16″ 1/4-28 1-7/8″ 2-5/8″ 5/16″ 3/4″ 20′
ST08A316C 3/16″ 5/16-24 1-7/8″ 2-5/8″ 3/8″ 3/4″ 20′
Engineered In America Every Hayn fitting is designed and manufactured at our facility in Rocky Hill, Connecticut — the same American workmanship that has set the standard for stainless steel rigging hardware since 1950.
Cold-Worked Production Hayn fittings are cold-worked, not cast. That distinction matters: the cold-working process refines grain structure, increases fatigue resistance, and produces a fundamentally stronger component — one built to perform when the load comes on it.
Precision Manufacturing Our Rocky Hill production floor runs CNC vertical mills, CNC lathes, large-capacity mill-turn centers, and waterjet cutting systems — all configured to produce hardware that meets exact specifications, every time.
75+ Years of Excellence Hayn has been engineering and manufacturing marine and architectural rigging hardware since 1950. That track record isn't just history, it's the design knowledge, failure data, and continuous improvement that goes into every product we make. 
  • Type 316 stainless steel construction for superior saltwater corrosion resistance
  • Manufactured in Rocky Hill, Connecticut to Hayn's proprietary tolerances
  • Precision-machined using advanced CNC manufacturing equipment



  • Engineered for seamless integration in marine and architectural rigging systems

  • Short lead times on both standard and custom components

  • Backed by 75 years of marine and architectural hardware expertise

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Let's Build Something Together

 Hayn has been engineering precision rigging hardware since 1950. So whatever your project demands, you're building with hardware that's been proven at sea and on structure for generations. 
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