VacuTight Ferrules are specifically designed size ensures sufficient nut/thread engagement even in shallow ports. Their unique flat-bottom configuration can prevent over compression and tubing ID reduction that can occur with many fittings. This results in consistent aspirating and dispensing volumes across all system connections. This ferrule is for use with 1/8OD tubing and can be used with M6 or 1/4-28 Flat-Bottom Port configuration.