IRWIN Strait-Line 2035102 24-Inch Magnetic Box Beam Level Vials will never break, fade, fog, leak or develop static charge for longer tool life Luminous backing for easier read in low light Plumb view vial for vertical applications Calibrate vials in seconds with simple turn of a Hex key or Philips screwdriver for less downtime Powerful rare-earth magnets for hanging level from steel studs or beams