These silicone squishy balls are fabulous.  If you love pop its you will really love these. They are actually easier to use than the pop its as you don't have to turn them over to push them out again. When you push one in, another pops out.    
Warning... like all pop its there is NOISE involved.  Not a good one for the class room or meeting room lol.  Another warning.... a tad addictive too!  
They are a great sensory tool, squishy with the added dimension of endless popping as you rotate in the hand.  
Please note that they can vary in colour from photo.