Product review (5 stars): Prevention is better than a clogged drain [watch out for knock-offs that are poorly made]
These are apparently the ones I got for over 25 years from my local grocery store [the package calls the product, "The Original"].  Very highly recommended [every plumber that I have used in the past 25 years had the same response when they saw them on my washing machine hose, "Great idea!"].  Unfortunately the local market now sells some knock-off copy that does not work [several of these opened up a rip from top almost to the bottom and each time it was on the back side where it was not visible!!!].  Watch out for cheaply made imitations...