<blockquote class='ipsBlockquote'data-author="ratter" data-cid="1345899" data-time="1357541903"><p> what if the stickers are placed in a slighlty different height, what if the base thickness of the glass is different these can have an affect on the reading, the quality control may be tight enough to stop these from occuring but a $25 tester will have limitations<br /> <br /> We have seen the same batch tested several times with the test tubes and given varying results</p></blockquote> Hey mate, If your putting the same amount of fuel to water the thickness of the test tube shouldn't matter I would have thought. Also, I agree with you about the stickers and could create issues. However it may be out by a couple of mm, but 5mm would be quite noticeable. Be great if the etched the lines into the glass rather than having stickers