Back Ferrule, 1/16", SS, 10/pk Back Catalog number: CTS-21679 Availability: In the manufacturer's stock Price on request - + Recommended CTS-21069 Frit Adapter, 4/pk Price on request CTS-21118 Filter Cartridge w/Lock Ring, Titanium, 2/pk Price on request CTS-21650 Performance Maintenance Kit, e2695 Price on request