M16 M20 M24 M30: 180° Pivot and 360° Swivel: Four 3/4" Dia. Shackles Four 1" Dia. Shackles Four M12 × 1.75 mm Bolts for 3/4" Dia. Shackle—2,310 lbs. Capacity and 19 mm Thread Lg. Four M16 × 2 mm Bolts for 3/4" Dia. Shackle—4,180 lbs. Capacity and 29 mm Thread Lg. Four M20 × 2.5 mm Bolts for 3/4" Dia. Shackle—4,730 lbs. Capacity and ...