The base is a clamp that's adjustable to fit the rim of the toilet tightly. Then there's a swing-up/down latch that clamps over the lid and seat keeping both of them down. You have to lift two buttons at the same time as you lift the latch, I found I could easily do it with one hand while holding a newborn, but my toddler, who could easily defeat all of our cabinet, drawer, and door locks just couldn't do it. Because I did it one handed the trick wasn't obvious.
Mommy's Helper Toilet Seat Lid Lock Mom's can't wait for their child to be potty-trained but don't want to see them playing in it. Until that times come, the Mommy's Helper Toilet Seat Lid Lock will keep toddlers out of the toilet. This Lid-Lok protects children from accidents, and keeps plumbing safe. There'll be no more toys to scoop out when you can keep curious hands from getting into the wrong place. Easy for an adult to open with just one hand, the lid lock attaches easily to most bowls and lids and is simple to remove when no longer necessary.