This is an ultrafiltrate system for use with Costar 50 ml tubes and Millipore filter of 0.45 um and 25 mm diameter. This system can be sterilized with gas, alcohol or ultraviolet light. The idea is to keep the liquid sterile all the time and not have to pass it from a sterile container to the Costar tube. The design is made to be easily printed and assembled using only epoxy glue. Another extra material is an O-ring of 25 to 27 mm in diameter. Instructions for assembly and use are in the "Instructions.pdf" file.