The CyberPower 4POSTRAIL 4 post rack mount rail kit provides a universal mounting solution for 1U, 2U, and 3U equipment weighing up to 231 pounds. The adjustable rails can be expanded from 18.5" to 29" to support various sizing requirements. The necessary attachment hardware is included. assembly, and material or workmanship. Contents: 2 Rails (Right and Left) M4 x 8 Screws (Qty. 6) M5 x 12 Screws (Qty. 16) FEATURES & BENEFITS 1U, 2U, 3U Support - The universal 4POSTRAIL kit can be used with 1U, 2U, 3U, and supports equipment that weighs up to 231 pounds. Adjustable Length - The rails adjust from 18.5" to 29" for proper fit into various sizing requirements. 4-Post Mounting - Secures equipment at both the front and back of the rack. Mounting Hardware Included - Sixteen (16) M5 x 12 screws are included to secure the rails to each post..