The phrase "extra assurance" means having more certainty or confidence in something. It means taking additional steps to make sure that something will happen or be successful. Full definition
Or use as pants over your diaper and cover anytime you want extra assurance of no leaks. (greenmountaindiapers.com)
There are many good resume writers that are not certified, but this is one way to provide you with extra assurance if you need it. (jeffthecareercoach.com)
There are times when you need a little extra assurance against leaks. (diaperjunction.com)