End fittings are Quenched & Tempered or normalized, bodies heat-treated by normalizing. Hot-dip galvanized steel. Turnbuckle eyes are forged elongated, by design, to maximize easy attachment in system and minimize stress in the eye. For turnbuckle sizes 1/4 through 2-1/2, a shackle one size smaller can be reeved through eye. Modified UNJ thread on end fittings for improved fatigue properties. Body has UNC threads. TURNBUCKLES RECOMMENDED FOR STRAIGHT OR IN-LINE PULL ONLY. Lock nuts available for all sizes. Fatigue rated to 20,000 cycles at 1-1/2 times the Working Load Limit. Meets or exceeds all requirements of ASME B30.26 including identification, ductility, design factor, proof load, and temperature requirements. Importantly, these turnbuckles meet other critical performance requirements including fatigue life, impact properties, and material traceability, not addressed by ASME B30.26. Meets the performance requirements of Federal Specifications FF-T-791b, Type 1 Form 1 - CLASS 4, and ASTM F-1145, except for those provisions required of the contractor. For additional information, see the warnings and applications section.