Beaker Bong Spiral Perc BlackGrace Glass Spiral Perc Bong Black The quality produced by Grace Glass will rival the most well known of brands out on the market today. This compact design holds a few key features every passionate smoker is looking for, a beaker base which provides more volume for water and also gives more stability to the piece at the same time. The main feature is clearly the black perc found encased within the glass chamber which twists around into coolant.