Strong but they have a limit.
I used these to hang tissues balls decorations from the ceiling.  We did have a couple decorations fall down, but most stayed up.  They were on an acoustic type of ceiling panel.  They weren't able to hold lighted Chinese lanterns very well from this ceiling though.  We ended up not using the lanterns because these dots couldn't hold them.  The good thing about these glue dots though is that they cause no damage to the wall or ceiling that you use them on, but they do have a limit to what they can hold.
Rating: 4 stars