New 5mm LEDs.  These are the slow fade variety.  They take about 30 seconds to go through the cycle of Red, Green, Blue, Cyan, Magenta, Yellow, White-ish.  All the transitions are gradual.  No rapid flashing.  They have a fully diffused lens.  They need 4V at about 10-20 mA.  As with all LEDs, you'll need to add a series current-limiting resistor if you have a supply voltage of over 4V.  

These are nominally 5mm in diameter, and will push into a 3/16" hole.  

The sale is for 50 LEDs.