Three large cable distribution spools are included with each 10”, 12” and 15” wide (250 mm, 300 mm and 380 mm) vertical cable manager (will not fit other sizes). Attaches inside vertical cable managers. Spools are 2.75” (69.9 mm) in diameter and 5.9”L (150 mm) and made from black plastic; each kit includes four spools and mounting hardware.