Welcome to the world of Coil Percs! Coil Percs, often called spiral percs are a stylish and scientific looking perc that offers enhanced smoke filtration over other options. These percs are made of long spiraling tubes the the smoke must travel through, often travelling with  cold water, which gives the smoke time to cool before reaching your lungs. These coils may appear as a perc or they are sometimes featured on the mouthpiece of bongs, usually glycerin bongs.