A level is only useful if you can read the vials. This level comes equipped with oversized 1/2" field-replaceable vials. Not only are the vials themselves easy to read, but the level has more vials than competitive models in 48" and longer lengths, meaning the vials are always within eyeshot, even at awkward angles. Finally, Johnson's SurroundView(TM) technology maximizes visibility and top read windows allow the user to stand over the work to view the vials.