What is the difference between ferrules made of stainless steel vs. stainless steel/PEEK hybrids?

Stainless steel ferrules are used when:

• Absolute maximum operating pressure is required, in excess of 15,000 PSI.
• The connection is ‘permanent’; that is, the connection will not be made and broken often, such as when changing columns.

The Stainless Steel/PEEK hybrid ferrule (called a high performance ferrule) is:

• Typically limited to 15,000 PSI with multi-ferrule fittings
• Limited to 10,000 PSI with a single HPLC nut
• Can be re-used a limited number of times if not over torqued, or if used on SS tubing