Twist one wrench to lock or unlock the entire set. Magnetic backing will attach to most metal surfaces. Holds up to 12 wrenches. Holds up to a 1" or 24mm wrench. Great for roll carts This red 12 piece wrench holder requires a simple twist of one wrench to lock or unlock the entire set. Magnetic backing allows this vertical organizer to conveniently attach to most metal surfaces. Designed to securely hold a variety of wrenches, SAE or Metric.