Tip up line markers

For years I've used small, red/white, clip-on bobbers to mark depth on my tip ups.

I've seen some advertisers selling shirt buttons, and have heard of people using the sliding foam bobbers you pin in place with a toothpick.  Has anyone tried the buttons, and are they easy to slide up/down?  Do you have a problem with them slipping and changing your depth?

I like bobber stops. Cheap and go through guide easily.

I've used buttons in the past. They work fine. I think I went back to bobbers because it's easier to just clip it where you need it rather than moving the button up or down. Not saying it's difficult to do that, just a little quicker.