These were great for a few weeks, but then the end piece started to pop off the ends of the laces every time we tried to tighten the slider. In order to fix this, you need a tool to pry it back open.  Super inconvenient, especially since the point is to save time tying my preschooler's laces. I'm kicking myself for tossing the laces. One of the sliders is also looser than the other, and doesn't keep the tie tight enough. I definitely wouldn't buy them again. I'd be better off buying $30 shoes that have a non-laceup design!