these bottles are hand made and are tested to ensure their functionality. the design of the bottle, and method used to innoculate and withdraw your liquid culture will dramatically decrease contamination rate. the luer lock fitting are bonded to the lid using a heat resistant apoxy resin to ensure it remains airtight after sterilization and normal wear and tear. included with each bottle will be a dry packet filled with my personal favorite liquid culture recipe. all you is and the water and then sterilize the bottle containing the luquid culture.