Recently. whilst installing my new pier, I unfortunately found myself in the position of not having a suitable level. I consulted the refrigerated reference centre - bingo! After some considerable physical research, the better brands such as Boag's have much better "squared" affixing of the labels, allowing a more precise reading, the meniscus of the contents just above the main label.
(Postscript - I have also tried using 375ml cans, but after 5 attempts gave up, useless)