Reagent fwj, tseem hu ua media fwj los yog cov fwj kawm tiav, yog cov thawv ua los ntawm iav, yas, borosilicate lossis lwm yam tshuaj, thiab topped los ntawm cov kaus mom tshwj xeeb lossis cov stoppers. Lawv yog npaj kom muaj tshuaj nyob rau hauv cov kua los yog hmoov daim ntawv rau lub chaw soj nstuam thiab muab cia rau hauv lub txee los yog nyob rau hauv txee.