A continuous edge center vial is accurate and easy to see.
aluminium, rugged box beam design is engineered for maximum
durability even after susraining a 2-story or 50-degree temperature 
change inside your vnhicle.
Plus, you cancalibrate vials in seconds with simple turn of ahex key or philips screwdriver

Size: 300mm/12", 400mm/16", 500mm/20",
600mm/24", 800mm/32", 1000mm/40",
1200mm/48", 1500mm/60", 2000mm/80"