500ml Kilner Jars 5 "Quality counts" Mrs Thorpe 21 October 2011 This was my first attempt at preserving so I decided to opt for a reputable brand of jar; and I'm glad I did. I managed to achieve a vacuum seal even though it took me a while to fill all 9 jars before putting on the lids. At first I thought the seal hadn't worked but, as the jam cooled, the vacuum kicked in (physicists explain, please). Follow the instructions included and all should go well. The "Kilner" name adds to the overall impression of quality - it might even make up for less-than-perfect contents... Good value too.