The Low Dead Volume Top is specifically designed to reduce the volume of media in the ports of the FCS2 from the point where the supply tubing attaches to the FCS2 through to the optical cavity where the cells reside for imaging. It is commonly used when working with expensive compounds and primers. Note: When using a Low Dead Volume Top, only the aperture and length of the tubes are reduced. The rest of the FCS2 is the same as the standard model. The following charts and examples illustrate the differences. The standard FCS2 has a minimal cross sectional area of 0.608 sq mm. The inside diameter of the vertical tube provides ample flow for most experiments; on the order of fractional to milliliters/sec. However, the lowest dead volume top has a minimal cross sectional area of 0.196sq mm.