This is the Repair Kit ONLY for the Pfeiffer PKR250/251 FPM Sealed Cold Cathode Pirani Gauge. Repair Kit Includes: 1 support ring, 1 O-Ring FPM 3.69 X 1.78, 1 O-Ring FPM 10.82 X 1.78, and 3 Ignition Aids. For detailed instructions on how to replace the Pfeiffer PKR250/251 maintenance kit parts, see .pdf to the side at Downloads, page 23. (This pricing is for the Repair Kit Only, pumps, controllers, sensors sold separately.)