Checkmate is scientifically formulated to detect the high levels of a certain enzyme found in a mans semen. Just follow the easy instructions. Using Checkmate means no traces of the test will be left behind and nobody will ever know the article was even tested. Everyone's situation is different so only you will know when is the best time to perform the tests. Just follow the easy instructions.
Undergarments are of course the best place to test, but like always every situation is different.
We have seen people do tests on the inside of shirts and blouses and on things like sheets, bedding, automobile upholstery etc. Be creative in your search. Checkmate comes in a plain white box that is safety sealed and double shrink wrapped. This small box is then placed inside another small white box that is also safety sealed and shrink wrapped. You can also have your package delivered to any other address of your choice, like a friend or relative.