Double Drum Perc BongGrace Glass Double Drum Perc Bong. Another new release from the devoted Grace Glass team, this tall double percolator glass bong shows the unwavering high standard that the glassblowers have set on glass quality and functionality. This huge glass bong comes equipped with two small showerhead percolators in the middle of the glass tube. Though small in size these percs are highly effective and considerably enhance the users hit. This great end result