If a container opening is closed with Seal-it, then the container cannot be opened without destroying the seal-it label. Seal-it is additionally provided with several cross-perforations which immediately tear when manipulated like a motorcar tax disc. Seal-it can be used to securely seal bottles, sample bags, sacks, specimen bags, envelopes, etc. The white labelling field on the seal-it can be written on with all conventional writing tools with, for example contents information, sampling date, name of operator, etc.