When using vertical gel electrophoresis devices, spacers are sandwiched between one notched and one plain glass to form the gel “cassette”. The notched glass plate provides a contact area for the buffer from the upper buffer chamber to flow over the gel to complete the electrical circuit required for electrophoresis. Note that the “ears” on notched plates are fragile, and should be handled with care. Extra notched and plain glass plates are available for all Galileo vertical units.