Extra thick walls give these polypropylene carboys added strength. Choose these carboys when service conditions are most extreme. Useful as vacuum trap, will hold full vacuum up to 8 hours. Leakproof and autoclavable. Handles on shoulders of carboy. For convenience, use with Nalge 2158 series Quick Filling/Venting Closure in vacuum applications. Supplied with 83B closure with TPE gasket. NOTE: For best results, autoclave using a properly vented closure.