Fitment: The heavy duty equalizer & shackle upgrade kit are compatible with double Eeye springs (3.5K -5.2K Axles). Material: Made of steel and nylon, wear-resistant, high strength, good impact resistance, can adapt to long-term outdoor environment. The use of anti-rust oil on the surface enhances the anti-rust effect and increases the durability. Performance: Thicker shackles, bronze bushings and greasable bolts to increase strength and reduce maintenance. Package: 2 Pcs Equalize and 1 Set of Heavy Duty Shackle Upgrade Kit(8 X Shackle Straps, 14 X Bolts, 14 X Bushings, 14 X Nuts). No instructions. Installation hardware are included. Installation: Bolt-on installation, easy to operate. Professional installation is recommended. Fitment: The heavy duty equalizer & shackle upgrade kit are compatible with double Eeye springs (3.5K -5.2K Axles). Material: Made of steel and nylon, wear-resistant, high strength, good impact resistance, can adapt to long-term outdoor environment. The use of anti-rust oil on the surface enhances the anti-rust effect and increases the durability. Performance: Thicker shackles, bronze bushings and greasable bolts to increase strength and reduce maintenance. Package: 2 Pcs Equalize and 1 Set of Heavy Duty Shackle Upgrade Kit(8 X Shackle Straps, 14 X Bolts, 14 X Bushings, 14 X Nuts). No instructions. Installation hardware are included. Installation: Bolt-on installation, easy to operate. Professional installation is recommended.