These syringes are for use with the ramé-hart Automated Dispensing System p/n 100-22 and the ramé-hart Oscillator p/n 100-28. There are currently (2) syringe sizes available: Choose 250uL for our standard syringe. Note that the 250uL syringe is the standard size and one ships with each new Automated Dispensing System (100-22). Choose 50uL if you need to produce small drops or are working with dynamic studies requiring smaller volumetric graduations between steps. The 50uL syringe is standard with the Oscillator (100-28).