The most commonly used micropipettes operates upon air displacement and the micropipettes are adjustable, but deliver a measured volume of liquid. The micropipettes are available with a single channel or with multiple channels as a multichannel pipette. Most multichannel pipettes are with eight channels, but they may also come with 12 channels or six channels.
A less common type of micropipettes operates by positive displacement. These positive displacement pipettes are suitable when handling problematic media e.g. viscous liquids such as oils and glycerol and also volatile liquids such as acetone and methanol. Find positive displacement micropipettes by Carl Roth.
Single pipette vol. from 0.5 to 5000 µl by Heinz Herenz
Single-channel pipettes from BRAND, vol. from 0.1 to 10,000 µl
Single-channel pipettes from Carl Roth, vol. from 0.5 to 10,000 µl