OK, so the BreakMaster is cool and can help you read and chart greens, and it can also help train your eye to read breaking putts... but is it LEGAL?
According to the Rules of Golf, it would not be legal to use the BreakMaster to measure a green during a stipulated round BEFORE you putt.
However, it is perfectly legal to use the BreakMaster AFTER you putt, to take measurements of a green and make notes on the Break Direction and Break Amount in a Custom Greens Book for future reference. After a few rounds of doing this, you will have the inside track on how each green breaks on that golf course.
It is therefore LEGAL to use your Greens Book notes during any stipulated or competitive round of golf. This is what Tour Pros and Caddies have been doing for years, and it’s one reason why they have such low scores.
So, to recap: it's legal to use the BreakMaster to make notes in a Custom Greens Book during a round as long as you do it after you've holed out. Use your Greens Book every time you play that course. It's easy, fun and absolutely LEGAL!
There is also a NEW RULING by the USGA and R&A that allows the use of Greens Books in competition. Read all about it HERE.