Premium file pockets feature plastic hooks that swing out to file on rails, stabilizing files in the drawer. Hooks swing down out of the way for active use. Unique double-reinforced, cross-bonded, rip-proof spun polyester gussets offer total strength and flexibility. Tops are laminated for extra reinforcement. Red fiber file pocket also has tape reinforcing strips at critical wear points. 3-1/2" expansion file pockets also feature a double-thick front, manila lined back and moisture-resistant coating.