The unique rack (# 3452) features support clamps that hold pipets in a perfectly vertical position. When used in conjunction with the acrylic leveling platform (# 3459), users are assured of the most accurate results. The durable acrylic leveling platform has a leveling bubble and four adjustable feet. It is used in conjunction with the ESR Rack with Support Clamps to ensure a completely leveling testing surface. Accessories include: 10-Place ESR Rack with Pipette Support Clamps Acrylic Leveling Platform 10-Place Polystyrene Rack Piercing Funnels ESR Transfer Pipettes