Ultra-pure, virgin PTFE chips promote gentle, efficient boiling and help prevent superheating, even of highly volatile liquids. Ideal for continuous extraction methods, such as EPA SW846. “Stones” minimize “bumping” during reflux and distillation. Not affected by boiling acids, hydrocarbons, ketones, esters, alcohols or alkalies. Easily cleaned and non-contaminating. Show no trace of acidity or alkalinity. Will not scratch or abrade glassware and leave no powdery residue. Usable up to 550°F (288°C).