Rubber Safety pipette fillers are designed for efficient one-hand operation, It eliminates the need of mouth pipetting of hazardous liquids. Air evacuation, liquid uptake, and liquid dispensing are controlled by three valves. Each valve has a chemically resistant stainless steel ball. Simply Pinching or releasing valves provides smooth liquid flow. Filler bulb accommodates standard size pipettes. Silicone is also more chemically resistant than natural rubber.