World Bowls Ltd. have in their regulations Section 8.2.2 the following - "To check the accuracy of the bias and visibility of the World Bowls stamp, all bowls should be re-tested and re-stamped at least once every 10 years, or earlier if the date stamp is not clearly legible".

So it is important that you know what the stamp on your set of bowls indicates.

If you have a set of bowls manufactured or re-tested after 1st. April 2002 then your stamp should look like the picture below. Note however that the letter will be that relevant to the manufacturer or tester and that the 10 years includes the year of stamping / re-stamping.

World Bowls Ltd Date Stamp -

This is the 'new' current (2013) World Bowls Ltd. registered stamp that was brought into force when all the testing facilities had the same test surface, same delivery mechanism and the modern Working Reference Bowl.

World Bowls Board Date Stamp -

Prior to the WB stamp was the Worlds Bowl Board stamp, commonly know as the 'bullet' stamp. This stamp was used from 1993 when the International Bowling Board was renamed and updated to the World Bowls Board. The information shown is basically the same as the current stamp.