The Bel-Bulb™ Pipettor is a simple suction device with a soft tapered chuck to fit pipettes from 6 to 8 mm in diameter. The flexible vinyl bulb is 5 cm diameter x 7 cm long (2" x 2 3/4"). After filling your pipette, remove the bulb and quickly cover the top of the pipette with a finger to hold fluid or release it as needed.