Stanley 142920 I Beam Spirit Level 3 Vial 600mm 24 inches Durable heavyduty I Beam aluminium level 2 x pfixed vials & 1 x 180& Acircº rotating vial top easy to read centre vial 600mm long with rule on one edge with window on top to view the horizontal level from above p Level is fully adjustable & so makes the ideal tool for a carpenter or roofer No estimating needed you can be sure that every timber is at an identical angle to the last