The ones I'm talking about are the ones with loose caps
What they mean by sterile is that when they were produced they were either put under a UV light or place in a high temperature vat. So by the time they are place in the packaging they are sterile. When you open the package it is up to you to keep the environment that you are working in sterile. When the caps are tight, it should be an air tight seal lowering the change of contamination.
